Drainage After finding the problem we use the best solution. Here we regraded the back yard first. Next we installed an underground drainage system to redirect the major water flow so it would not be seen. Then we constructed the patio over everything and sealed the patio with Gator Sand. This way we not only have the proper grade under, but any excess rain water will run off of the patio as well. We correct all kinds of drainage problems. Some we can do by just grading, while others we have to incorporate a drainage system. We will only do what is right to correct your particular situation.