Originally Posted by sdhrst04
Can we not just have the water and toilet go directly to the sewer line?
Do we have to do these hose things.
You have to hook up a drain system to drain the sewer tanks. The normal way with a travel trailer is to use a flexible sewer hose with the correct connections at each end. You could connect and disconnect the sewer hose each time you drain the tanks. But if your TT is not expected to move very often, then you can build a more permanent drain system using 3" PVC pipe.
There are two types of 3" PVC pipe, ordinary water pipe and sewer drain pipe. The sewer pipe uses gentle angles which requires longer pieces of angle pipe connectors. But you can probably use the shorter water pipe angles for your drain system. You definitely want to use the 90° angle water pipe connector to turn the drain pipe down into the sewer pipe in the ground, because the sewer pipe 90° angle connector would raise the drain pipe too high in the air.
Buy a 3" or 4" connector that will screw onto your main drain valve and connect to 3" PVC pipe. Plus a connector that will screw into the drain pipe in the ground and convert sewer pipe into that connector. You'll probably have to buy those pieces from an RV supply source. But the rest of the PVC pipe and angle connectors you can buy at any big-box hardware store/lumber yard such as Lowe's or Home Depot.
In addition to the PVC pipe, you'll also need 3" PVC pipe angles of 45° and 60° and 90° to route the pipe from your drain valve to the sewer dump. Don't try to bend the pipe, use the angle connectors to make it go the direction it needs to go to reach the sewer dump pipe. Then at the dump pipe end, screw in a 3" connector to transition from the pipe to the dump. (That 3" connector replaces the cap on the dump station.)
Don't use PVC pipe glue until after you have all the pieces cut and assembled to be sure it's going to work without straining any of the connections. In fact, mine isn't glued together at all. Just hand-tighten the pipe joints together as tight as they will go by hand. Be sure the pipe has a good downslope angle from the trailer to the sewer dump. If you don't have excellent eyeballs, then use a 4' carpenter's level to be sure you have a good slope from trailer all the way into the dump pipe.
I have an RV trailer set up that way outside my house, for elderly sick daughter to live in. That final 90° turn to go down into the sewer pipe means the rest of the pipe has to be up in the air some to have a good angle from trailer to dump. You may need to raise the trailer some to get it high enough off the ground to have a good angle for draining the trailer tanks.
Support the drain pipe at every connection with lengths of 2x6 or wider lumber, stacked up to the height required to support the pipe, with no more than a few feet between supports.
As others noted, the grey water valve can be left open except when draining the black water tank. The black water tank valve should stay closed except when draining the tank. You can look down into the toilet to see if the black water tank needs draining, but don't forget to look regularly.