Please feel free to contact us direct about Swan Industries, Inc.’s RV Plumbing Parts if you have questions that are not answered on this page How often should i use my San-T-Flush System? We recommend you flush your system each time you dump your holding tank. It is highly recommended to use our San-T-Bottle (aka San-T-Flush Injection Bottle) in conjunction with our San-T-Flush system for the best clean. What can cause the San-T-Flush vacuum breaker to leak? A couple things that can cause the vacuum breaker to leak: 1. Debris. Any type of debris that goes in through the inlet can get stuck inside the vacuum breaker causing it to not seal off properly. 2. Not winterized properly. 3. Low water pressure. We recommend at least 40 psi. Note: Back-seepage upon shutting off the flow of water is normal. If water is turned back on before the water recedes fully then you can experience a small amount of water coming out the top of the vacuum breaker. When i am using your San-T-Tabs will I need any other chemicals for my holding tank? You do not need to use any other chemicals in your tank. Between flushings you can drop one San-T-Tab into the black &/or gray tank to manage the odor. Also… how many tablets you use to flush your system can vary on individual usage. You may need a second tablet if it’s been a long time since you flushed the system or if you have heavy usage. We do recommend you flush the system each time you dump your holding tank. This prevents buildup of waste and debris. When using my water fill in "city water" or "local supply" mode, why does my fresh water holding tank fill with water? Generally we find that a build up of water mineral deposits on the check valve (the one located either in or near your water pump) is the most common reason your tank fills with water as the check valve isn't preventing back-flow into your fresh water tank. Water minerals can build up inside and prevent it from working properly. If your check valve is not the cause, the next recommendation is to clean or replace the 3-way ball valve as the same thing can happen with it. Again, the water minerals can wear down on the ball inside and eventually cause it to leak (this usually happens around 20 years +/-) . Why is my hot water heater still filling with antifreeze while the valve is in "bypass" mode? Typically this is a result of a build up of water minerals in the check valve that is located where the hot water comes out of your water heater. Locate this check valve and check it for excess water minerals. These water minerals can hold the check valve in the open position therefore not preventing back-flow into the water heater.