I know that it can be very frustrating to have issues with your toilets while it's raining. Depending on whether you are connected to a sewer system or a septic tank will determine what the problem is. If you are connected to a sewer system, when there is damage to it, water from run off infiltrates the sewer system and overloads it. This will cause your toilets to drain slowly or not at all. The system is not flowing fast enough to drain them. The city/county that you live in, is responsible for fixing this. Get them to install a backflow preventer on your sewer line to prevent this. If you are connected to a septic tank then you are responsible to fix it. A septic tank is always fairly full, they overflow at the very top out to the distribution box and field. The field works by absorbing water and evaporation, neither work well if the ground is saturated. If its been more than 5-8 years since the last clean out then have it pumped. Also the drain field for the tank, needs to be check as well. If the field in saturated or broken down, then the water from both the rain overloads the tank. Once the field drain properly, the toilets will drain. I hope this helps. If you need further assistance, please reply to this thread. Thank you for using Manage My Life.