How to Make Functional Koi Pond With Waterfall

13 Materials
2 Months

I have read many tutorials on Hometalk and other sites with instructions on how to make a pond, waterfall, or water feature. Many (not all) of these tutorials make it sound very cheap and easy. Naturally I thought to myself, how hard can this be? I just need to dig a hole in the ground and throw a cheap liner in there. No problem, right? Maybe buy a pump for a waterfall.... I might add a filter when I get some extra cash. I'm a fairly competent human and my kids like digging. I can get this done in an afternoon. These thoughts led me through late spring and were buzzing through my mind the day my husband asked me: "What do you want for your birthday?"

After a short conversation, we decided we could afford to spend $300 on this project. We could re purpose an above ground pool liner instead of buying a pond liner. I found a cheap pump on amazon for $120 (or we could use the sump pump if we wanted to). I estimated $0 for rocks because we could get them free on Craigslist. I estimated $180 for plumbing pipes, PVC glue, pretty plants I had been drooling over during mothers day, and maybe I could get a handful of fish. Six weeks later, we had spent $2500 on this project. None of the above actually happened that way. I do not actually enjoy needing to do excessive research for projects. I tend to just jump in and get it done. Can't do that with this project. I had to actually plan things. Crap.

So before you read any more, please take a moment to seriously decide if having fish in your pond is important to you. If it is, please read the following about fish in ponds. If not, skim only if you have nothing better to do.


When you are building a pond with the intention of putting fish in there, please read a bit about them first on your own. Research them. Seriously.

Koi and goldfish are related to carp. They are extremely friendly fish. You can pet them and they even have personalities. They will eat each others eggs, but are never aggressive toward each other, except when the males want the females to lay eggs, then they will beat up the girl fish until they produce. The baby fish will never be harmed by the adults. Carp, Koi, and Goldfish start pretty small, but they grow very fast. Carp look just like solid black koi or goldfish. the only noticeable difference between the goldfish and koi that I've noticed is that koi have the cute little mustaches and seem to cost a lot more. The butterfly koi have really amazing tails compared to standard koi. If you want a cheaper option with the fancy tails, you can buy a shebunkin or comet goldfish, which do great in koi ponds with other fish.

Be careful about the liner that you buy. Many pond liners that are ordered online can be toxic and kill all your fish. You don't want that, so please think seriously about whether or not you can afford to skimp and buy a cheap liner. We ended up buying a cheap one for $300 and our fish are fine, but we could have just as easily ended up with dead fish.

When you have fish, you need to make sure that your pond is deep enough. It needs to be at least 2-4 feet deep in order for them to survive. I live in Southern Oregon, and we have hawks and blue herons and raccoons that may try to fish in our pond, and having a deeper pond (4 feet) allows the fish to hide at the bottom, out of harms way. It also protects them against freezing temperatures. These fish seem to be very hardy and can survive living in a frozen solid pond, but added depth provides potential for a bit more heat, so its important. If you live in a particularly cold climate, please consider purchasing a pond heater for added protection.

Fish will get very stressed out if they are in full sun without shade. They need to have the water slightly aerated, so having a waterfall is important. They like to play at the base of the waterfall. Having a lot of water plants is very important. Plants provide shade and a safe place to hide from predators. It is also the most likely place for fish to lay eggs.

Something that is really lame about ponds is algae. It definitely has it's purposes (covering the folds in the liner), but when your pond is in bloom with algae, you can't see your fish. You can't see anything really. Your pond will look like a large puddle of pea soup. Not very pretty., and makes you feel like you wasted your summer and money. In order to combat this, I recommend going to an actual pond specialty store and talking to an actual human and investing in the biggest, baddest, most expensive filter you can find and make sure you get a really good warranty on it. We did this. It cost $500 which was way more than we had expected. It seriously saved the project. It has an amazing UV filter that kill any of the floating algae so our pond was crystal clear all summer. Many people recommend the barley bales to combat algae, which you can also purchase in a liquid form. This is entirely harmless toward your fish, but watching it used in other ponds, it didn't really effect much. You will have to clean your filter often. It was recommended daily by our local pond store owner, but we have managed weekly during the summer because of the quality of the filter. the lower the quality, the higher the maintenance will be.

Oh! Before I forget, a great way to combat the predators is to order a motion activated sprinkler system. It sprays them whenever they get close and you don't have to cover your pond with ugly nets!

Have I scared you away from this project yet? Or was it Too long, didn't read?
Our Waterfall with Jurassic Lettuce in Front
Step One: The very first thing you should do is figure out where you want your pond and how deep you want it to be. Select a good clean area. Be aware of trees that might be nearby or specific invasive plants. The roots of my wisteria could puncture the lining, so I will need to dig it out soon. It's important to me to have a tree behind the pond to provide shade, but I was really worried about the roots, so I planted it in a planter box my husband made.

We laid a string around the border of where we wanted the pond and played around with it for awhile. We decided that we wanted it a little larger than we had initially imagined. There was a concrete sidewalk and a concrete patio that were in the way. We spent the first weekend removing them. It was not enjoyable. At this point I was super excited that we were going to build a pond.

I really wanted to go out and buy koi immediately. What I should have been focusing on, was checking out Craiglist for free rocks. So while my husband and sons were taking a sledge hammer to the patio, I was emailing people in my city looking for free rocks. We borrowed a truck and picked them up. It was an entire pickup bed sized truckload of free river rocks.

After we unloaded them onto a tarp, I began calling all the carpet companies in my city. Dennis, the pond store owner had recommended that we find some free used carpet remnants or carpet padding to place under the pond liner to protect it. I succeeded and loaded up my mommyvan as full as I could. So far, we had successfully kept to budget.

So now we have a spot located. We have a few supplies. Can we break ground yet please? Of course not.
Step Two: I don't want to rain on anyone's parade, but now we need to do the safety/code/inspection stuff. Let's start with the common sense thing... call before you dig.

In the United States, you can call a 611 number and the city will send a whole bunch of companies to spray paint where important things like power, sewage, plumbing and gas lines might be. This is pretty important stuff. If you hit your water main... you had better be prepared to spend a small fortune on hiring a plumber. In 2016, my son was helping me dig out an area for a pebble mosaic spiral labyrinth and he stepped through a rusted lid of a septic tank that had never been legally abandoned. The city did not know about it. He could have been seriously hurt. It's not just dirt below ground.

After calling 611, please call the city planning department and tell them about your plan. Make sure that you don't need a permit and ask about codes regarding fencing. This seems like a minor thing, but some cities have codes about man made bodies of water. City codes can vary depending on depth or size. If there is a city code in place that you do not follow, you may need to correct it before you can sell your home. Even if there is not a city code in place, you really need to consider fencing if you have kids that will be near your pond. My father in law (former paramedic/battalion chief) has pulled several children's bodies out of backyard ponds because people didn't want to ruin the view of their pond with a fence. IF YOU HAVE KIDS/WATCH GRANDKIDS THIS IS A NECESSITY! NOTHING IS WORTH THE POTENTIAL LOSS OF A CHILD.

Of course I didn't actually want to build a fence, but within 12 hours of us putting water in our pond, my father in law was right there installing hideous chain link fence for safety. And yes, I know that most people have fond memories of waterholes in their youth and think safety fences are ridiculous, but these ponds are extremely slippery and our world today is not the same world that existed 20 years ago. I know I don't trust my kids near it without a barrier.
Husband (Aaron) Removing Concrete Patio
Step Three: If you intend to order a pond liner online, now is a good time to order it so it can ship while you are digging. We ordered a 20'x25' liner off of amazon for $300. Keep in mind that if you will have koi or fish of some kind, many plastic/vinyl liners can be toxic for fish, and you might end up with sick or dead floaters in your pond.
Twins Emily (left) & Bella (right) Helping
Hit Granite/Discovered Random Concrete Chunk
Step Four: Decide if you want to bust out your shovels and pickaxes and cause your biceps to triple in size or if you would like to rent heavy equipment. If you will be having help hand digging your pond, go out right now and buy them a case of beer, or pizza, or bottle of wine, or whatever they like, because its really difficult labor. We (of course) tried to hand dig it. Aaron (my wonderful husband) dug and dug and dug. We had measured out a 10.5 ft by 12.5 foot oval. We decided that we would place a plant shelf about a foot down. My oldest son Gabe (12) helped a bit. They got about a foot deep in two days... my fabulous weekend warriors! So far, still havent spent any money on this project. The next weekend, we got another foot down, then hit granite. Granite is not fun. In three days, they chiseled out about 4 inches deep in about a 2 foot circle. Patience is not my strongest attribute. I was not pleased with the slow progress. I convinced Aaron to rent a small handheld jackhammer the following weekend. It cost $80. We rented it for Friday afternoon through Monday morning and sent it back exquisitely cleaned. It carved out the rest of the pond in a few hours. Four weekends and we finally have our pond dug!TIP: Many rental companies will charge you only for one day when you rent an item Friday afternoon and return it Monday morning.Side Note: Yes, Aaron's biceps really did triple in size this summer from all the digging. It was pretty awesome.
Our Living Waterlily
Step Four: We laid the carpet down in the giant hole. It took about two hours to smooth everything out around the funny edges and weird cuts. I know it sounds weird to lay carpet under a pond, but its really great protection against sharp rocks or roots. It will not mold or get damaged. My in laws replaced their pond liner after five years and the carpet under their liner was as perfectly clean as the day they installed it. Go ahead and lay the liner over the top. spend a good amount of time smoothing this out, so it lays as flat as possible. Algae will cover the liner in a few weeks, so if you can see folds, don't worry because the algae will make them invisible. Make sure you pull about an extra foot over the edge of the pond for overlap. If you have a skimmer box, use a razor/box knife to cut a square in the carpet and liner for the spillway of the skimmer box to connect. seal it together with the included screws and glue.

Step Five: This is a short easy step. Fill your pond with water. It would be smart to turn off all of your water using devices and actually check your water meter to find out exactly how many gallons your pond is when filled. Check it before and after to see how many gallons you used. While the pond is filling, decorate the rim with river rocks or whatever type of decorative stone you have available. Make sure you cover all of the visible liner. This is purely for aesthetics.

TIP: If you are planning on buying fish for your pond, try to find a friend that already has a healthy pond and get him to give a you a rock from the bottom. His algae covered rock has a ton of really healthy pond bacteria that will encourage growth of a healthier habitat for your fish. If you don't have a friend with an extra pond rock, start adding water plants that have been sitting in funky pond water as soon as possible. Wait a week after you add water and an algae rock/plants before adding fish. Hose water contains chemicals like chlorine in it which will distress/kill your new fish. By the end of your week, your pond will be filled with billions of microscopic organisms that contribute to overall pond health. It will also be smart to buy a water testing strip kit to make sure that the ph balances and chemical levels are appropriate for your fish. Step

Six: Yay! Time for shopping at the pond store! Pond stores are sooo much fun! Ours is called In Thee Garden Dennis, the owner, is a walking encyclopedia of information on building ponds. While he was explaining to my husband the importance of quality filters and skimmer boxes, I was picking out the waterlily above ($25). I also bought one head of Jurassic Lettuce ($6; which seriously took over most of our pond within two months) and a few water hyacinths ($8 for two). We bought an amazing filter with a UV filter thing ($500), a decent pump ($200), a skimmer box ($300), a waterfall spillway box ($35) and a bunch of plumbing supplies. I think the plumbing supplies (tubing, valves, boxes, pvc glue, fitting, etc) were around $200 but quite possibly more. So now including equipment rental, we have spent almost $1700... only $1400 over budget, right? *facepalm*

As I mentioned in my fish section, having a high quality filter is extremely important if you want to actually see your fish. Without a good filter, your pond will look like it's filled with pea soup. A skimmer box pulls all of the surface material away. It cleans all the leaves and dust and random twigs, etc. It will need a separate pump. Skimmer boxes aren't a necessity, but it is nice to set up at the same time as your pond, if you can afford it. We have set up ours mostly, but have not bought a pump for it or actually used it yet. As far as main pumps go, we chose to purchase a submersible pump. You can buy an inline pump that you can set up in a garage or barn or pump house if you wish, but these require much more preparation and have fallen out of fashion in the past decade. I would recommend buying a pump that will circulate all of the water in your pond every hour.

Step Seven: Hope you haven't put your shovels away yet. Now we get to trench. Please hold your enthusiasm. Our goal here is to trench along the edge of the pond, going to our barn where we keep our filter. We need to lay electricity to power the submersible pump and we need to lay PVC pipes to get the water from the pond to the filter to the waterfall with an extra line so we can easily drain the pond if needed. Aaron did all of this. there was a lot of frustration and I made sure to keep his Pale Ale stocked and cold. He ended up creating a valve system under the waterfall so we could turn off the filter/waterfall and it would send the water to the street drainage. Please map this out thoroughly. Hire assistance if needed or get help. The pipes go together just like irrigation pipes. you just cut them with PVC cutters and glue them together with the purple and blue primer and glue.If you have a skimmer box, make sure you plumb some pipes attaching from the skimmer box/pump to the filter so that the water that it pulls will be cleaned. I'm sorry there aren't more details regarding plumbing and electrical work. I'm really not an expert in those areas.
Failed Attempt at Waterfall Construction
Step Eight: This is one of those times when I worked really hard all day then hated the result, then worked really hard again and failed again until succeeding with the third try. Building waterfalls is a lot harder than it looks. All we had were free Craigslisted river rocks and a small mountain of huge concrete chunks from when we tore out the patio. I really tried hard to use the concrete chunks as a base. One of my personal life goals is to try to minimize my carbon footprint as much as I can.

The first time I built it up, the concrete chunks were fairly uneven. The waterfall would wobble and it I was afraid that it would topple over if s large bird landed on it or the kids threw a ball at it. I spent an entire day carefully placing the rocks to cover up the pond liner and making three shelves for the water to spill over. The vertical spaces between the shelves and the sides of the waterfall were the most difficult to maneuver. The rocks kept falling down.

We finished, and I didn't like it, so the next day I disassembled the whole thing while Aaron was at work and started over. The second time, I built it up much more stable with the same concrete chunks. I thought a taller vertical drop for the waterfall would look nice. I made it very stable and it looked good, but it was impossible for me to get the river rocks built up the front side where the water spilled out. I climbed in the already very slippery pond to try to adjust the front rocks. Not the smartest choice with my cell phone in my back pocket. Failed this waterfall attempt also.

Final try... Not even going to try to use the concrete blocks this time. I found some of those partially curved large cement blocks that people frequently use for fire pits or landscaping walls. They were removed from our front yard during the spring. I stacked them up in a cave formation over the valve box, completely hiding it. I placed a board, creating the first shelf. I placed some bricks on the shelf edges to create a guided waterway. I repeated it again for the next shelf, and then placed a few solid bricks on that platform to support the waterfall spillway. I was a bit frustrated with the river rocks. My husband and I went to a rock supply store to buy a few decorative base rocks to cover the shelves and to create a very solid base around the walls of the waterfall. We spent another $300 on the cheapest larger rocks we could find and it turned out pretty good. I worked a bit fitting them together and creating nice clean edges so all the liner was covered. To be honest, I still haven't finished the rocks on the waterfall.

A common problem during this step is that the water will not flow properly over the rocks on the waterfall. There are two ways to fix this. You can mortar the rocks in (mortar is like glue for rocks, cement is not) which has to be done and dried before you put water or fish in your pond. Mortar is toxic for fish before its dried and solid. Playing with mortar will dry out your hands severely and mortar contains lime which is very dangerous. Use rubber gloves and possibly a face mask. The second option is to buy some of that black foam spray (looks like a can of spray paint) that is specifically designed to blend into the liner and support rocks while forcing the water to flow over the rocks. Your waterfall should be completely dry before using this. The black foam stuff will allow you to change the placement of your rocks at a later time. I have not done either of these methods, I have just read about and talked about them with other pond owners.Attach the pipes that lead from the filter to the waterfall spillway. Make sure your pump can handle whatever height your waterfall is. Turn on the filter and pump and seriously... take a break and enjoy for a bit.
Funky Chainlink as Temporary Barrier
Step Nine: If you have kids or live in an area where there are codes regarding fencing, think about what kind of fence you would like to have. We have a temporary chainlink fence providing safety while we finish our real fence. I chose a nice iron fence with vertical poles. It hasn't been finished yet. We have a friend that recently removed a railing from an outdoor porch. It was exactly the perfect amount of fencing in order to wrap around the circumference of our pond. Our fencing is 32 inches tall, which I believe will be the perfect height to prevent my littles from climbing it. It's white and rusted and the angles are not perfect, but it's a lot of free fencing. Now we get to learn how to weld! So Aaron and his dad went shopping and bought the posts. Aaron's dad (Arlen) brought his welding stuff over, and taught Aaron how to saw and sand metal and weld the pieces together. I made sure none of our kids looked at the little blue welding flame because it can permanently damage their eyesight. We got a few panels welded together. The plan to secure them into the ground is to bolt them into poured concrete bases. We also finished two 3' gates, one for behind the waterfall and one for the edge next to the skimmer box which happens to be close to our back door. Arlen retired from the fire district and opened up an auto restoration shop, so he has all the welding supplies needed for an iron fence. He plans on helping finish the welding part (which has been on hold for about two months because of other projects). Then Arlen will sand down the fence and spray paint it black for us in his shop. Having amazing in laws is something I am very grateful for.
First Dragonfly (Danaerys), Made a Home Here
Step Ten: Landscape around your pond. Create shaded spots for fish. Frogs will inhabit your skimmer box (sometimes they come home on nursery water plants). Dragonflies will breed... a lot... it's rather fascinating to watch. Create an amazing eco system. You can buy fish locally or order them online. The ten cent feeder goldfish will grow up to be as large as koi if you really want to fill your pond on a budget. The shebunkin and comet goldfish have amazing tails, like the butterfly koi, and of course all koi are stunning. Talk to pet stores about what you will buy. Frequently, in the summer, ponds are filled with so many baby koi that the owners just want to dump them. This is a great time to get a ton of free fish.We also created a small stone foot path behind the pond (along the hedge) so we can access the skimmer box and waterfall and have a place to stand when releasing or catching fish. Keep in mind that with fish, it's wise to change out part of the water frequently. We usually drain a few inches, then refill every three weeks or so. This pond was completed in early August, and it's only late October now, so it isn't very old and I have not experienced it through all four seasons yet, but I have enjoyed my in laws pond since I met my husband 8 years ago, and much of my knowledge comes from them.
Butterfly Koi That I Caught in Arlen's Pond
Some of the plants I planted include:

Paulownia or Empress Tree: Fastest growing tree in the world with huge giant leaves that get to be two feet wide. and scented purple trumpet like flowers. So far mine has grown four feet tall since I purchased it as a seedling four months ago.

Lotus Flower: Cost a lot! $50. It has beautiful white flowers in late May. I tried ordering the cheap chinese seeds and none actually sprouted, so I splurged and bought a live one in full bloom.

Water Lily: Check to make sure that the type you buy will be healthy in your grow zone. I bought a pink and yellow one that seems to be fairly hardy in zone 8 where I live, There are also tropical varieties, which seem a bit prettier, but I didn't want to risk it dying over the winter.

Jurassic Lettuce: I bought this because it has a cool name. I think this is an annual. They float on top of the water and provide a ton of shade for fish, insects, and frogs. My single head turned into seven plants in a month, and had taken up over half my pond in three months. I had to thin them out drastically. They make great compost.

Water Bamboo: I bought this because it looks exactly like the small native reeds that grow along the creek near the my favorite summer campground, about 30 minutes from Crater Lake. The above dragonfly is perched on it.

Dinner Plate Dahlia: Transplanted from front yard to spot just to the left of waterfall.

Monkey Flower: This stuff grows like crazy all along the Rogue River and makes me smile when I go rafting. I transplanted some from my in laws pond. Some monkey flowers seeds traveled with the water hyacinths they purchased a few years ago, and the plants took over their pond. They have already taken over our waterfall, and have cheerful yellow flowers similarly shaped to snapdragons.

Water Hyacinths: A floating annual with spiked lilac colored blossoms, very inexpensive and fun to watch expand.

Pacific Giant Beauty: I think that was it's name... it was a very tall plant that added a nice height to the background of the pond with very lush bright orange flowers. The roots began to outgrow and literally break through the one gallon pot it came it. I transplanted it to a larger pot and placed it on the plant shelf in the pond. Within two more months, the same thing happened. I pulled the muddy mess out and separated it into three plants, placing them bare root in a triangle around the pond in the water. They are all thriving.

Chinese Lantern Plants: I bought one of these guys a year ago and it spread sooo fast! I transplanted a few of the babies into an area around the planter box with the tree in it as filler. The lantern parts kind of shriveled up during the transplant but the leaves are green and thriving. This is an extremely invasive plant, use carefully. I love the bright orange lanterns that it produces each fall.

Portulaca: I had a bunch of seedlings sprout up this year in various planters left over from last year. I just threw them in to add some temporary color. Portulaca is supposed to be an annual, so I expect them to die down during the first serious frost.Chinese

Wisteria: It's the really tall guy in the front. I planted this from a seed five years ago when we first bought our home. Unfortunately, I have to dig him up this weekend because the roots are very invasive and can destroy the pond liner. Hopefully, I can replant this in a pot. If it doesn't survive the transplant, root damage and abuse, then fortunately I harvested about forty wisteria pods last week so I can plant a new one.

Oh! I also was gifted some floating sea glass orbs and bought an awesome cast iron mermaid to decorate. I hope to add some floating lights in the future.
You can see part of the 'new fence' that we are still working on above. on the right. We recently excavated the entire front and left side of the pond to create a paver stone patio around it.

Next summer we hope to build a pergola as well to create shade for the fish, shade over our patio, and provide a barrier between the harsh sun and the back part of our home where it glares through the windows. After we build the pergola, I want to replant the wisteria to climb up it.

To the right of the pond (not pictured) is a play fort with slide and sand box that we designed in google sketch up and built for our kids. We spread small pebbles as ground cover in their play area.

I hope you enjoyed this tutorial. I apologize if it was too long. I wrote it primarily as a heads up that building a koi pond is MUCH more difficult than many tutorials suggest. I like to think I am fairly competent at figuring out how to do things, but I would not have been able to do this without extensive help from my husband and his parents and Dennis at the pond store.

Suggested materials:

  • Pond Liner  (Amazon)
  • Filter  (In Thee Garden)
  • Pump  (In Thee Garden)
See all materials

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