Lew made mention of a flush valve problem we had on the trip to FL, but once we get past the toilet jokes we get to the serious core of the issue.

The following applies to Head Hunter toilets and flush valves but may also apply to other products.

In the plumbing industry the cardinal sin is cross contamination. Every single plumbing code in the country has extensive regulations to prevent the possibility of waste water entering the fresh water supply system. Our coaches with the aforementioned toilet and flush valve would likely never be accepted by any of the building codes relating to plumbing. I am sorry for the length of this, but it is important for all coach owners to completely understand the following otherwise they might as well brush their teeth with water from the toilet, unless they already have.

The HeadHunter toilet operates by having a very high volume flow of water create a low pressure to evacuate the toilet bowl. A diaphragm valve is caused to open, the flow of water is actuated and in a short period of time the valve closes and the water stops flowing. The problem begins if the flush valve fails to turn off the water flow. The response is to turn off the pump or municipal water supply. Here is where every owner needs to look at his or her coach. If the water supply to the toilet can be isolated and shut off while maintaining pressure in all other water systems in the coach (such as the sinks and shower) there is a potential for cross contamination but it is slight.

If the only way to turn off the flow to the toilet is to shut down water flow to the entire coach you may have a serious problem. When the house water pressure drops to zero with a flush valve that will not shut off the flow to the toilet, the valve is open. With zero house water pressure and a ball type check valve in the water system it is probable the toilet contents will backflow, through the flush valve, and into the fresh water tank. It is less likely if the coach is equipped with a spring type check valve. All chack valves are more efficient if the water pressure on the downstream side is much higher than that on the upstream (pump) side.

If you store your coach with the pump turned off and the water pressure bled off the potential to create this contamination condition exists. The only sure way to prevent cross contamination is if there is an air gap between the water flow source and the soiled water, and with the toilet design that is not possible.

I never studied my system when it was working but when it failed to shut down on the trip to FL I studied it to determine how it worked and I now have a fresh water supply to sanitize. The toilet and valve are elegantly simple and as such should prove very reliable, and are very easy to service, but since the toilet will backflow into the fresh water tank under certain conditions it would be wise for everyone to at the very least understand their own coach system and determine if they can assure themselves of a means of prevention.