Published on October 21st, 2015 | by Henri0
Well water stains patio
Q. We have installed a sprinkler system and well to use for lawn watering only. Every year, our patio turns black. When the house is power-washed, the patio is cleaned as well, and it looks great. However, as the months go by, it turns black again.
Could the well water be causing this and, if so, what can be done to prevent it? Can something be applied to the concrete to prevent staining?
A. The well water is definitely the culprit. The staining can be from iron or manganese in the water, but it is interesting that it can be cleaned by power-washing, as these chemicals penetrate deeply into the pores of the concrete and are almost impossible to remove, unless the concrete has been sealed and is resealed regularly.
Another possibility is tannin staining from decomposing vegetation that could get into your well, if it is a shallow well. Tannin stains would easily be removed by power-washing. To find out which of these is causing the problem, have the water tested by a water specialist who will offer suggestions for solving it.
You may also want to consider sealing the concrete after a thorough cleaning every couple of years. Your local hardware or building supply store can sell you the right product.by