dougrainer wrote:
OK, NONE of the answers to WHY it is needed are wrong.
1. There is NO way the black tank can backfeed to the fresh system as long as all connections are to factory install and use while camping. There is NO cross connection to the fresh system at all.
2. The REASON the check valve is installed and the REASON it is HIGHER than the Black tank is to keep Black tank odors from migrating back out the Inlet in your water bay. Most OEM installs the inlet does NOT have a check valve like the check valve on the City Water inlet. That is designed so when the black tank flush has completed, when you remove the pressure hose, you will see about a pint of water flow back out. That is fresh water in the line up to that check valve. Then the check valve keeps the odors inside the tank.
3. Aftermarket Black flushes have the check valve either at the tank inlet or the connection has the check valve like on a City Water connection, so there will be NO check valve under the Lavy sink. Doug
2012 Monaco dimplomat had the valve under the lavy sink I know because it leaked and I bypassed it for my friend
