Installing the Nature’s Head composting toilet in a Sprinter

We just bought the Nature’s Head composting toilet. After testing it out in our spare bathroom for a week, we installed it in our van. Here’s how we chose to fit it in.

We’re in the process of redesigning our van interior. Rather than using the stock crew bench in the third row position, we’re going to add a bench seat against the window behind the driver’s seat. We decided to put the toilet in a box opposite this to form another seat, so it’s ended up in the sliding door area.

That might at first seem weird – who’s going to want to poop with a window right there? – but the windows are very well tinted and it’s the best place for the toilet in our setup.

Testing the toilet before we installed it

We’ve never used a composting toilet before. Even though all the reviews are very keen to point out that the toilets don’t smell in normal use, we wanted to be sure. So we set ours up in our guest bathroom for a week and used it pretty exclusively.

Nature's Head toilet set up in our guest bathroom
Nature’s Head toilet set up in our guest bathroom

In the picture, you can see the vent tube from the toilet attached to our ceiling fan. That worked OK, except the roof vent for the ceiling fan has a flap that stays closed unless the powerful fan is working. The tiny 1″ computer fan in the toilet wasn’t strong enough to open the flap, so we think we got some smells from the vent tube back into the bathroom.

Other than that, the toilet performed really well. Apparently we pee a lot, because we managed to fill the pee container up in just over a day of continuous use. The Nature’s Head site suggests that the container should last for about three days. We found that is true if you’re only using it at night and in the morning, and peeing elsewhere during the day.

Install location and box

The toilet isn’t going in a bathroom in the van because we don’t have a bathroom. Our shower is outside the back doors. Our sink is next to the sliding door. So, we decided to build a box around the toilet and just put it where it made most sense.

Initially we planned on putting it in the area where our bench seat had been bolted in, back in the third row seating position. Unfortunately the dimensions didn’t quite work out. It’s a shame, because it’s a slightly more private location and it would have created a great step up to the bed platform. We may still move it there in the future if we really find it doesn’t work out where it is now.

To fit the toilet in, we ended up with a 21″ tall cabinet in the sliding door space. It’s a little tall for sitting on, but it works well as a temporary seat and also as a transition countertop between the space inside the van and the outside world.

Cabinet with folding front flap
Cabinet with folding front flap

For the moment, we’re using a prototype cabinet built of 1/2″ plywood scraps and using road case aluminum extrusions for the corners. These things are great! The 1/2″ ply slots into the extrusion and you can just fix it in place with some self-tapping screws from the inside. It’s definitely sturdy enough for prototyping purposes.

Inside the cabinet, there’s space for the top half of the toilet to hinge open backwards so we can remove the pee container. There’s also space to the side of the toilet for the vent tube and the handle for the poo stirrer.

The empty toilet cabinet
The empty toilet cabinet with the vent pipe installed through the floor

The foil faced foam on the floor is acting as a spacer. We have a piece of L-track running on the floor under this cabinet. It’s what the cabinet is bolted down to. However, it stands proud of the floor by about 3/16″. The toilet has to balance on the L-track when it’s in place. To stop the toilet from wobbling, we put the foil faced foam down on either side of the L-track.

The toilet in place in the cabinet
The toilet in place in the cabinet

We have temporarily run a power supply for the fan from one of our 12v cigarette outlets in to the cabinet space. Later, if this all works out, we’ll tap into one of the spare power lines we ran when we wired the van.

Venting the toilet

Composting toilets need to be vented outside the van. The Nature’s Head comes with 5 feet of flexible hose with 1-1/4″ connectors on the ends.

Venting turned out to be relatively simple. We used two 1-1/4″ ABS bulkhead grommets to run the pipe through the box we’d built in the step area and then through the vertical metal wall of the sliding door step. These grommets have slip fittings, so it’s easy to just slide some 1-1/4″ pipe into them, and attach the flexible hose that is provided with the toilet to the pipe. You need a 2-1/8″ hole saw to cut the right sized hole in the floor of the van for these bulkhead grommets.

Vent goes through our sliding door step box and then out through the wall of the step area
Vent goes through our sliding door step box and then out through the wall of the step area

On the outside/underside of the van, we made an end cap from a Tee fitting, some aluminum screen door mesh, and some small lengths of 1-1/4″ pipe. The circles of screen door mesh slot into the ends of the T, and then the short length of pipe pushes in to hold them in place. We found that a friction fit was good enough, although you could always glue them if you wanted to. Theoretically the toilet itself has a screen on the outlet vent pipe, but we wanted to stop bugs from even getting that far.

1-1/4" Tee fitting modified with bug screens
1-1/4″ Tee fitting modified with bug screens
Tee fitting in place on the bulkhead fitting through the sliding door step wall
Tee fitting in place on the bulkhead grommet through the sliding door step wall

The one issue we had is that the fittings on the toilet itself are not 1-1/4″. Although the instruction manual says to use 1-1/4″ fittings, the rotational moulding is undersized and a regular 1-1/4″ PVC street elbow fits too loosely. We wrapped a couple of turns of tape around the fitting so that the PVC corner had a good friction fit.

Tape around toilet vent cap to make a regular 1-1/4" Street Elbow fit
Tape around toilet vent cap to make a regular 1-1/4″ Street Elbow fit

The toilet itself has two L-brackets that screw into the floor and then attach to the toilet base with thumb screws. They seem pretty sturdy. The toilet doesn’t weigh that much, even with the coconut coir and poo inside it, so we’re pretty confident that it’s secure enough.

Turning the cabinet into a seat

The final thing we did was re-used an old Ikea seat cushion on the top of the cabinet to make it into more of a seat. The cushion had Velcro on its underside, so we just stuck a strip of Velcro onto the cabinet lid to hold the cushion in place. So far, so good for our prototype cabinet.

The toilet cabinet with its Ikea seat cushion Velcroed in place
The toilet cabinet with its Ikea seat cushion Velcroed in place

We’ll live with this setup for a couple of trips before we commit to re-building the cabinet using 80/20 aluminum extrusions and bamboo 1/4″ ply like we did for our sink cabinet.

4 Replies to “Installing the Nature’s Head composting toilet in a Sprinter”

  1. We all know the real reason you put the toilet there is so you can slide that door open and enjoy the view from the throne 😉

    1. Ben, the vent works just fine in its current position. The vent fan is designed to run all the time, and that creates enough flow to keep any – uh – “gasses” moving through the system. In fact, we’ve found that we don’t even need the fan running full time and we still don’t get stinks in the system.

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