One of the most common reasons for a drain to back up is when flushing a toilet or running water down other drains in the house is because there is a blockage in your sewer main line. This can be caused by many different things, including grease, tree roots, and other debris. If you are experiencing this problem, it is important to call a professional plumbing service to have the blockage cleared as soon as possible. Otherwise, the backup could cause serious damage to your home and property. Another very frequent cause is a bad water pump which doesn’t allow enough water into your home’s pipes at any given moment in order to accommodate all of the demand for it inside your home. Sometimes this can happen if you live near a river or stream where sudden floods can push more water into town