We were really excited to get the plumbing done and test out the system. Unfortunately, we finished the plumbing during a Vermont winter and we wouldn’t be able to test it out until months later when we could make it to the south. Once it was up and running, we were overjoyed and have cherished it ever since. Let’s walk through how we put it together from where the water enters the system to where it drains.

In this post:
Fresh Water
Gray Water
System Test

Fresh Water

We chose a 46 gallon fresh water tank because we wanted to be able to be off grid for a significant amount of days without needing to leave for water. We also knew that more often than not, we wouldn’t fill the tank completely to the top because it increases the likelihood that water will back up or be thrusted out of the vent when we are driving. We also don’t need to be carting around that much weight on a regular basis — only when we expect to be in a remote location with no water source. One gallon of water is 8.33 pounds, so a full tank of 46 gallons would weigh just over 383 pounds.

Our tanks have 4 fittings on one side: two 1-1/2 inch female fittings and two 1/2 inch female fittings. We faced this side towards the back of the bus since the opposite side would be butted up against the wheel well.

We also used liquid nails to secure a layer of rubber underneath the tanks and some of the “garage” space in our bus. This helps to waterproof the area and create some friction underneath the tanks instead of putting them directly on our slick tiles. We also secured our tanks using metal L brackets to brace them.

Tip: Each of the fittings were put together using RectorSeal No. 5 Pipe Thread Sealant. This is used for plastic to plastic fittings or plastic to metal fittings. The general rule for plastic to metal fittings is that the plastic fitting should be male and the metal fitting should be female. This is because metal male fittings secured into plastic female fittings can strip the female threads and therefore cause a leak. 

Here’s how the fittings played out.


  • Top left (1-1/2″)
    • 1-1/2″ male to 3/4″ female fitting, 3/4″ male to 1/2″ female fitting, 1/2″ male to 1/2″ barb hose elbow

From the barb hose elbow, we connected a 1/2″ reinforced nylon hose with a metal hose clamp and routed it up the back corner of the passenger side. We then covered the hose with a custom made wooden piece to fit the corner.


  • Top right (1/2″): Fill
    • 1/2″ male to 1/2″ hose barb elbow

From the hose barb elbow, we connected a 1/2″ reinforced nylon hose to the back of the Shurflo water fill valve and secured both sides with a metal hose clamp. We built a wooden mount for the fill valve to be fitted to and screwed it to the bed frame so it would hang below the bed in the garage space.

Emergency Drain

  • Bottom left (1/2″)
    • 1/2″ male to 1/2″ male fitting (“nipple”), 1/2″ female to 1/2″ female ball valve, 1/2″ male to 1/2″ hose barb

We wanted an emergency drain on the fresh water tank in case we found that the water we filled was not okay to drink or if we ever need to empty the tank. Of course, you could just use the water pump and drain the water through the whole system but that ends up taking an excessive amount of time and energy when you have a 46-gallon tank. We left the 1/2″ hose barb fitting without anything on it and if we need to use the emergency drain, then we connect an extra piece of 1/2″ reinforced nylon hose with a metal hose clamp and open the valve.


  • Bottom right (1-1/2″)
    • 1-1/2″ male to 3/4″ female fitting, 3/4″ male to 1/2″ female fitting, 1/2″ male to 1/2″ male fitting (“nipple”), 1/2″ female to 1/2″ male elbow

Here’s where it gets more complicated! For our fresh water setup, we created a shelf to sit on the fresh water tank. We used scraps of thin plywood that we had no other use for and screwed them together so that they would be thick enough for the water pump and accumulator tank to screw down into. We slid the shelf into notches we made in the vertical bed frame supports around the fresh water tank. We put the strainer, pump, and accumulator about as far back on this shelf as the first silencer hose would allow so that the remainder of the shelf could be used as garage space in the future.

From the 1/2″ male elbow, we attached the first of two Shurflo silencers that are used to quiet the sound of the water pump. This silencer has two 1/2″ female swivel fittings. We connected the other side to the Shurflo strainer, which connects directly to the Shurflo water pump, then to the Shurflo accumulator tank, and then to the second silencer hose.

Tip: The strainer filters out any little rocks or debris that may have made it into the hose and water tank. The accumulator tank creates a pressurized water reserve so that the water pump does not need to run constantly when you're using the sink. 

Despite the accumulator tank, we still find that our water pump runs very often, so maybe we need another accumulator tank or just a bigger one. Despite the silencers, we also find that the water pump is still pretty loud. We plan to retrofit a silicone pad underneath the water pump to help minimize vibrations. Others have also suggested making a soundproof box for the water pump. Always more to do!

After the second silencer hose, we moved onto 1/2″ PEX! We used a 1/2″ male to 1/2″ plastic PEX fitting. A lot of PEX fittings are metal and we didn’t want to deal with the metal-to-plastic fitting issues, so luckily we were able to find plastic PEX fittings ordered through Ace Hardware. From the 1/2″ plastic PEX fitting, we added a crimp ring to secure the PEX from the side of our bed over to the closet. Here, we added a T PEX fitting where one outlet would go to the sink and the other to a sprayer in the “garage” space.

For the PEX going to the sink, we used a 90 degree bend support to get it through the closet and into our kitchen cabinet. From here, we used another T fitting with one PEX fitting and two male fittings. These male fittings were connected to the cold and hot female fittings attached to the faucet. We decided that cold water was good enough for us, so we do not have a water heater.


We decided to have a sprayer that we can use out of the back door of the bus so that we can easily clean ourselves, our shoes, the bus, and any other dirty items before bringing them into the bus. From the PEX hose, we used a 1/2″ PEX to male fitting and then a 1/2″ female to 1/2″ female ball valve to a 1/2″ male to 5/8″ flare fitting. From this flare fitting, we can attach a regular garden hose with a spray nozzle.

Gray Water

We chose a 21 gallon gray water tank because we knew we’d be able to find dump stations pretty easily and we would make it a priority to drain the gray water tank as frequently as necessary. Just like our fresh water tank, the gray water tank has 4 fittings all on one side that we placed facing the back of the bus.

Here are the gray tank fittings.

Sink Drain

  • Top left (1-1/2″)
    • 1-1/2″ male to 1″ PVC slip joint, 1″ PVC, 1″PVC slip joint to 1″ PVC slip joint elbow, 1″ PVC, 1″PVC slip joint to 1″ PVC slip joint elbow

Let’s take this directly from the sink back to the gray tank fittings mentioned above. When you buy a sink, it has a hole in the bottom that you need to put a drain in using plumber’s putty. Once this is in, the bottom side of the drain has male threads. A tailpiece washer, slip nut, and tailpiece screw onto the sink drain. At this point, you have a tailpiece sticking straight down from your sink. The HepVo attaches directly onto the tailpiece with its compression fitting.

Tip: The HepVo replaces a P Trap, usually found in houses, with a short tube and diaphragm that prevents backflow of air and water into showers and sinks. P Traps take up more space and have to be installed in one orientation. They work in houses because houses don't move but in a vehicle, water could potentially slosh back through a P Trap when the vehicle accelerates or stops abruptly. The HepVo is smaller and can be installed horizontally or vertically. Its internal diaphragm makes it a one-way valve so that water and smells can't come back up.

Unfortunately, our HepVo didn’t come with any installation instructions. We were hoping that the HepVo would attach directly onto PVC pipe. We brought it to the hardware store and tried to attach different sized PVC pipes but none of them fit. It took us quite some time to figure this out. Eventually, we learned that we needed to attach a chunk of tailpiece to the outlet of the HepVo and then use a compression to 1-1/2″ PVC slip joint adapter. This is a standard adapter and we could not find a 1″ PVC slip joint alternative, so we had to add yet another fitting to get it to work with our 1″ PVC system.

We decided to use 1″ PVC because we felt that 1-1/2″ was excessive for our small bus and we knew we would be very careful about what went down the drain (we use a strainer to make sure practically nothing but liquid goes down). Our drain for the tank is 3/4″ anyway, so having a 1-1/2″ inlet to the gray water tank and only a 3/4″ outlet inevitably means that things would be getting stuck in the tank if we did allow them down the sink drain.

The issue with attaching a 1-1/2″ slip joint to our 1″ PVC is that you would need a chunk of 1-1/2″ PVC to then use a 1-1/2″ PVC slip joint to 1″ PVC slip joint adapter. This would have worked, but we did not want to buy just a few inches of 1-1/2″ PVC if we could avoid it. That’s when we learned about hubs and spigots.

Hubs are fittings that PVC piping goes into while spigots have the same outer diameter as the PVC pipe. So, we bought a 1-1/2″ PVC spigot to 1″ PVC hub and suddenly we were in business! Due to the angles underneath our sink, we lastly needed a 1″ PVC 45 degree hub elbow. We attached this assembly to our 1″ PVC pipe, which directly attached onto the fittings on our gray water tank.

To connect PVC piping and fittings, you need PVC primer and cement. This is smelly, toxic stuff, so we recommend wearing a mask! The primer is applied to both sides of a fitting or pipe first so that they can loosen up and then the cement is applied quickly after to permanently attach the pieces together.


  • Top right (1/2″)
    • 1’2″ male to 1/2″ hose barb fitting

Just like the vent on our fresh water tank, we attached a 1/2″ reinforced nylon hose to the 1/2″ hose barb fitting using a metal hose clamp. We then ran the hose to the back driver’s side corner and up the wall where we covered it with a customized wooden corner piece.


  • Bottom left (1/2″)
    • 1/2″ male plug

We had no use for this extra fitting, so we plugged it up!

Tank Drain

  • Bottom right (1-1/2″)
    • 1-1/2″ male to 3/4″ female fitting, 3/4″ male to 3/4″ male fitting (“nipple”), 3/4″ female to 3/4″ female ball valve, 3/4″ male to 3/4″ hose barb fitting

For our gray water drain, we wanted the hose to go under the bus because we didn’t want to drain our gray water and then store the dirty hose in our “garage” space. However, we also didn’t want to leave a long stretch of hose under the bus because we knew that would get grimed up and dirty from driving. Our solution was to route the drain under the bus with a hose that runs about 5 inches under the floor of the bus. Because this section is short, it stays higher up and doesn’t get too dirty when we drive. When we find a dumping station, we attach a longer hose with a barb to barb hose fitting. When we’re done, we take the hose off, run clean water through it, and then we feel good about storing it in our “garage” space. For some people, this may just seem convoluted or like it’s extra effort but we’re happy not to have a dirty hose that’s always attached to our tank inside the bus. We’re also happy to not have to detach and reattach the hose inside our bus as well.

System Test

When we made it to the south and finally found the time, we filled our fresh water tank and tested the system out! We hooked up our 25 foot potable water hose to a spigot, let it fill to above the outlet for our water pump, and turned the water pump on.

Unfortunately, water sprayed EVERYWHERE in our cabinet next to the closet. This is where the PEX met the T fitting for the faucet hoses. We had to run it a couple of times to find exactly where the leaks were coming from. It turned out that everything we personally did was perfect and the leaks were coming from the fittings that came already on the faucet hoses.

Fortunately, we were able to simply tighten those fittings and the leaks stopped. We were happy enough that although the leaks caused a bit of a mess, it was only in one spot and we were able to clean it and fix it quickly enough. WE HAVE WATER!

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