Remove heavy rust stain from our well water from house siding?

You can use white vinegar to remove water, mineral deposits, and rust on nearly everything. Try it on your siding. And only use the white vinegar as it's the strongest.

Table vinegar, either white or apple cider is typically 5% acidity. "Cleaning vinegar" is typically 6% acidity - yes that 1% makes a difference. And "agricultural vinegar" is 10% - 20% acidity, (not recommended for this project.) Make a paste with vinegar and baking soda and scrub away, and rinse immediately. Cover your plants and have a hose ready as vinegar will kill anything it comes in contact with - hence the paste and immediate rinsing, less liklihood of harming your plants. Do a test patch first, then proceed.

If not too bad, Dawn original and a scrubbie sponge might work too.

Good luck! Fingers crossed to you.

Maybe CLR cleaner would work.

You could try vinegar and baking soda, but honestly, vinegar will kill all the plants nearby. I use it as a weed killer, but it's non toxic for you, so cover the ground with plastic and rinse well and quickly.

White vinegar and lemon juice — which contain acetic acid and citric acid, respectively — can help remove rust from vinyl siding. Since they're natural ingredients, they're also safe to use. For your cleaning solution, mix ½ cup white vinegar (or lemon juice) with ¼ cup baking soda and 1 gallon of warm water.

Hello, hope this helps you out. For your cleaning solution, mix ½ cup white vinegar (or lemon juice) with ¼ cup baking soda and 1 gallon of warm water. Use a microfiber cloth to wipe the solution on your siding. Let the solution sit for about an hour then wash away with soapy water. It will kill plants if it makes contact so be sure to cover them before beginning.