So your ready to attempt the plumbing in your camper, you’ve probably put some flooring down and built some nice cabinets. Now you have to figure out what parts to buy and join together out of the thousands of plumbing parts available. It can be mind boggling, I remember what it was like when I started renovating houses spending hours in Home Depot trying to figure out what pieces go together. The last thing you want is a bunch of leaks ruining your nice flooring and cabinets, so I’ll try to make it look easy for you, here we go.
We’ll start with the fresh water tank, most RV fresh water tanks seem to be made of polypropylene. Some tanks are made from ABS but I’ve read that ABS is not food grade safe so only use ABS for RV grey or black water tanks. What I’ve found is that nothing likes to stick to polypropylene, even Sikaflex just peels right off when it’s dry. So whenever you have to screw in a barb fitting just use a generous amount of Teflon Thread Tape, even if your filler tube is a little loose on the filler barb, wrap some tape around the barb first as that will work better than trying to compress the tubing with a hose clamp, it works wonders. Don’t over tighten the plastic threads as this will cause leaks. If you are mounting your tank under the floor you can buy some 1/8” x 1 1/2” galvanized steel and bend it to shape around the tank and bolt it to the chassis to hold it in place.
In the photo above there is a 1/2” Barb with some white food grade reinforced 1/2” flexible tubing, this runs all the way to the water pump without any joins in it. The large black 1” hose is the Filler hose that also needs to be food grade. Above that is a clear 3/8” plastic breather (Vent) hose, this also needs to be food grade. The vent is in the top of the tank so you can’t see it in the photo. The Filler and Vent hoses should both run together up to your filler point and the Vent should be slightly higher than the Filler point, as in the photo below. When you fill your tank you tend to fill all the way up the filler hose, and if your vent doesn’t come up as high as the filler, water will leak out the vent and you’ll be on your hands and knees trying to figure out where your leak is coming from, so spend a couple of extra bucks and run the vent tube as high as the filler spout. Having the vent tube ending where you can see it is also handy so you can make sure it isn’t blocked with dirt. Some filler spouts come with a vent attachment, the one in the photo didn’t so I just drilled a hole so that the vent tube would just squeeze through. The filler should be mounted a couple of feet higher than the tank in order to get a good fall in the tube while filling otherwise it will take too long to fill the tank. Don’t try to avoid using a vent, you will have nothing but problems. If your tank doesn’t have a vent you may have to drill a hole in the top and add a tube, however your better off buying a water tank with a threaded vent hole.
Now we come to your RV water pump, I recommend the Shurflo 4008. I’ts fairly quiet, it can handle being run dry, it can draw water up from 6 feet and it automatically shuts off when you turn off the tap. The Shurflo 4008 also has a one way check valve so that your pipes don’t drain back into your tank, this is important if you have a hot water system. You don’t need to have an accumulator tank with these pumps either, what more could you ask for?
Mount your RV water pump somewhere so that you can screw it to the floor to minimize vibrations, I mounted ours in the floor of a closet. Before you attach your flexible water line to the pump, you will need to attach the Shurflo Inline Filter to the inlet side of the water pump to catch any dirt or plastic debris from your tank, if you don’t use an Inline Filter you’ll void your warranty. The picture below is the Shurflo Filter with a half inch barb to accept half inch hose. These can be purchased with thread either side, then you can add a 90 angle if you need to. You don’t use thread tape on this fitting.
If you have mounted your RV water tank under the floor, you’ll need to drill a hole in the floor and run your flexible tubing through it and attach it to the water filter on the suction side of the water pump. On the outlet of the pump you need to add a 1/2 ” NPS to a 1/2” barb fitting so you can attach another foot of the same flexible tubing. If your pump doesn’t have a built in check valve you will need to add one just past the pump on the pressure side. The pump I mentioned earlier has the check valve built in.
Depending on your budget you could add an accumulator tank, pictured below, just after the water pump if you have the room for one, but with a good quality pump you don’t really need one.
Now that your on the pressure side of the pump you could add a tee piece into the flexible tubing and add a Shurflo Pressure Regulated Water Entry such as the one in the photos below. If your on a budget you can leave this part out. The Shurflo Pressure Regulated Water Entry allows you to attach a hose at a campground to the outside of the camper so you don’t need to use your tank water or water pump. They have a built in pressure regulator which is vital if you have a RV hot water tank, they also have a one way check valve. If you buy an RV hot water tank, check the maximum pressure allowed and make sure your pressure regulator has the correct pressure for it.
Water entries like these also require a foot or more of flexible tubing to smooth out vibrations and make the system quieter.
If you decide to use a Pressure Regulated Water Entry in your system you’ll need to purchase a 1/2 ” barb like the ones in the photo below. Then you can attach a length of 1/2” flexible tubing to it and run back to your Tee piece in the main line just after the pump.
Now that you are a foot or more past your water pump and have added your (optional) pressure regulated water entry and accumulator tank, you can adapt from 1/2” flexible tube to 1/2” pex tubing. The reason you need flexible tubing either side of the pump is that it reduces vibrations and the pump will run quieter. Shurflo does sell a flexible tubing kit that will attach either side of the pump, however its probably a bit cheaper buy a roll of 1/2 food grade hose and a couple of clamps.
Sea Tech and John Guest both sell 1/2” fittings that fit 1/2” pex tubing. The photo below shows a john guest adapter with 1/2” barb to 1/2” pex tubing
When using Pex tubing you need to invest in a plastic tube cutter because your cuts have to be neat, square and free of burrs, this is very important so that you don’t have leaks. You push the tube firmly all the way into the fitting then you can add a retaining clip as demonstrated in the photo below. The end 1 1/2” section of tubing has to be in perfect condition with no scratches, if it has scratches trim it back to a clean section. There are O rings inside the fittings that seal against the outside of the tubing.
If you’re installing an RV water heater you should run your Pex tubing near the heater and add a Tee fitting as pictured below.
From the Tee fitting, run tubing to the bottom inlet of the water heater. This section of tubing should have a one way check valve like the one pictured below. This is so that water can’t drain out of the tank causing damage to the water heater. The RV water heater must always be full of water when turned on. Run tubing from the other outlet of the Tee fitting towards your faucets.
From the top outlet of the water heater, attach the red pipe because that line will be the hot water, run that pipe towards your taps. If you use red tubing for all of your hot water lines you’ll make less mistakes and it will look more like a professional job. There are two threaded fittings you will need to buy that screw into the back of the water heater that adapt to the 1/2” tubing. On Suburban Water Heaters they use a 1/2 ” NPT male thread. The fittings pictured below are made by John Guest. I think Sea Tech also make one that will work. Use thread tape on these two fittings.
Now you can run your blue pipes to your cold taps and red pipes to your hot taps, use 90 degree angles for extra sharp corners and Tee pieces to branch off to other faucets as so on, be careful not to kink the tubing. There is a bracket you can use for sharp corners (pictured below). Use tubing brackets to support your tubing.
In the photo below the two the steel braided hoses came supplied with the kitchen faucet, they have 1 /2” female swivels and I’ve just added a 1/2 ” pipe nipple then a John Guest 1/2” CTS x 1/2” female NPS. Unfortunately not all faucets have the the same feed, some have 1/2” male NPS and some have 3/8” compression fittings. If your faucet has 3/8” compression fittings you can buy an adapter from 3/8” compression to 1/2 NPT that will attach to a Sea Tech fitting.
You can use either Sea Tech or John Guest, however John Guest is English and they have metric BSP fittings and American style so you have to be careful when ordering that you buy the right size. If your in the USA it’s probably easier to use Sea Tech fittings. It is best to try and use 1/2” size fittings throughout the project if you can. You can use house hold faucets, and this may save you some money, however RV faucets tend to be lighter and keeping the weight down is important too. I hope you found this helpful.
I found a great instructional video on Sea Tech fittings just CLICK HERE.