We recently bought a farm with acreage with a manufactured house on it...We have two bathrooms, the water in both the bath tub and the shower, in both bath rooms do not drain all the way, you can see water when you look down the drain. It is also causing some bugs to appear (little bugs like no-see-ums). We have a septic that it drains into but there is not a big slope. What is causing this problem and how do we fix it?