When it rains I have water under one side of my house. Because the lot slopes it all ends up on one side. I think this is due to the septic drain field in the back yard being higher than the lowest point under the house. The drain field is far enough away that there is no oder problem but the water could cause other problems. I can put a french drain at the lowest point under the house but will this realy correct the problem? If this will work, how dept should I dig? I can dig to a level below or even with the footing if this is needed. Will I have problems later?