I need to redo the deck over my septic tank. Can I use concrete?

If you plan to sit the deck on the concrete, you will need to pour footings. To access the septic tank you will have to pull up your deck boards. I would put some skirting around the deck to keep the critters out.

Hello. Septic tanks often need to be serviced depending upon the age of your system. Actually in my community we are required to be pumped out every five years.

I would not consider this in my situation as I have recently replaced my distribution box and add a new lines to my system. An alternative solution might be to install some lattice work or screening so that critters and problems do not collect under there but the screening is removable is servicing might be required.

Poured concrete is permanent and will limit the access if you need to get to the tank. I would fill the space with cinder blocks or stacked pavers instead. Or you could have a wooden skirt build there to block entry.

are you talking about the actual top of your septic tank or a deck that is built over the septic? I would never cover the septic area with concrete due to maintenance issues

I like Kim's suggestion. Cinder blocks, stacked patio blocks, or pavers around the perimeter. You could also screw wire mesh to the deck perimeter and sink it into the ground about six inches, then a border of block.

As long as you can easily access the septic it should be fine

You need to be mindful of the weight as well. You might want to put down something like a steel to hold the weight of concrete off the tank. I would think piers and closing in the space with panels would be a safer route.