Installing an off grid water system

I'd set myself a task this year to finally get running water in my workshop as having no close access to it was slowing down certain aspects of my work. Since I'd been working on converting my van into a camper partly last year, most of the research had already been done, and I already had some parts going spare, like my pump, tap, and a few fittings.
One of the main challenges would be including hot water into the system, especially on a tight budget of £300.
This diagram is a retrospective look at the correct way of assembling this system, as the original diagram I worked from was incorrect for the final thing. It ended up being more of a guide as I figured out the rest in practice. I will discuss the mistakes I made as much as the way that did work, because it was a useful learning experience.
The whole system is fed from a water butt outside, collecting rain water from the roof of my workshop, which is siphoned into a 120L tank inside my workshop. Water is pumped directly from this tank by a camper-van diaphragm pump which is powered by a small 12V battery, and is automatically activated by a drop in pressure caused by a faucet being opened. The hot water is provided by an under sink water heater, which works like an electric shower.
All the wastes flow from the sink into a 10L jerrycan, which I then have to empty manually into a sewage drain as needed. 

Sink and faucet:

I had originally intended to have the sink in the corner closest to the door of the workshop, however that was also the corner furthest away from the water butt, so moving water to that area would have needed a more powerful pump. This is one of the problems of retro fitting, especially as I hadn't intended on installing water in the original plan at all, but the space where it was eventually installed turned out to be the most ideal anyway as it's not only in the dedicated "wet" area of the workshop (as indicated by the 3 inch layer of plaster caked onto the work surface), but it was also close to an otherwise unusable cavity that was the perfect size for a water tank. 

Once I'd cut the hole for the sink into my worktop, I had no choice but to become 100% committed to completing this project.

The tap itself was a fairly simple installation as it came with all the necessary fittings, it just pops through the hole, rods and all, and then tightens from underneath. I thoroughly cleaned the work surface and then piped silicone around the edge of the sink to seal it. I will eventually tile a back-splash around this space to protect the plaster wall, there are cheaper and easier methods to finish the wall off, but I figured going all the way will also be good practice for when I get around to fitting the new bathroom.

Cold tank and pump installation

The selection process for the cold tank went something like this: 

"search on ebay for campervan water tank" 
"measure available space under counter" 
"buy the largest tank within budget that I could fit in that space"

this size just so happened to be 120L.  

In some setups, the size of the tank might matter more, but as I have a 160L waterbutt outside feeding the whole system, plus an additional 160L butt waiting to be installed, and it never goes more than 2 weeks without rain around here, I constantly have a good store of water on rotation.

The main thing I have to be wary of with the tank is the fact the diaphragm pump works more efficiently with a sealed system. The biggest mistake I made when setting this up for the first time however, was sealing it without any kind of pressure relief overflow. I filled the Tank, then during a cold night, the water expanded and blew through the sealant, with the siphon still active, more water came in and began to overfill the tank, basically flooding that corner of the workshop. I have since fitted a pipe with non-return valve as an overflow, which drains outside.

For the pump, I used the SHURflo trail king 10. I had this pump left over from my camper build as it was excessive for the size of my van (I opted for a whale submersible pump for that instead), however it was a good size for this build and more importantly, well past its 30 day return period so I didn't really have a choice but to use it.

The fittings: 
  • flexible pipe: is 12mm flexible hose as recommended for this pump, This is more applicable in a campervan because that also moves, but the vibration from the pump alone can damage rigid pipes and fittings. 
  • The isolator: (John guest speed fit) at the start and end of the pump system, stops cold water from the tank being able to enter the system if maintenance is needed. 
  • Connection fittings: (John guest speed fit) they're really handy for flexible pipe, just push into place and they seal well.
  • Filter: (sold separately from pump) to protect it from debris. Obviously with a rain water fed system, installing this was essential, but bare in mind, even in a clean water system the filter still needs to be installed if you want full warranty on the pump. It's not expensive, so it's worth it. It comes with its own fitting to attach securely to the pump, but needs an additional fitting for the pipe.
  • Accumulator: which is expensive (there are cheaper alternatives to the official one however), it's purpose is to even out the pressure in the system and allow the water to flow consistently from the tap, and its also a refuge for excess water in the pipes when cold weather causes the water to expand, protecting the pipes from damage. All in all, it makes it so the pump can run more efficiently, saving power, protecting the system and expanding the life of the pump.
  • Check valve or Non-return valve: (John guest speed fit) prevents water from the heating feed from flowing back into the system.
  • Battery and charger: This is where I had the most issues. Not the 12V, its easy to convert 12V to mains voltage with a converter like a laptop charger for example, which was my original plan. I wired the positive and negative of the pump to a female DC jack, which I then tried plugging into a laptop charger. The pump was just on, all the time, but not actually doing anything. The issue was that Pump needs at least 4 Amps, but the charger would only give 1.5, as most standard chargers because... well laptops just don't need that many amps. After some research, I discovered that 12v to 24v converters at 5amps are expensive, but mini 12v batteries aren't, so why convert it in the first place? I bought a small 12v scooter battery for £30 and a smart charger for £12, hooked it up. Worked perfectly. 

Feeding the beast

I bought a cheap little siphon pump, and it now hangs out on my counter top, I need to find some way of mounting it or something because its just... THERE, all the time, probably the least thought about detail of the build and it shows.

One tube goes outside to my water butt, and then the second tube goes down into my water tank. I make two swift pumps then gravity does the rest! 

To finish off the outside, I insulated the tube with some foam campervan insulation, fed that through a 22mm PVC pipe and then insulated that with foam pipe insulation to protect the tube from frost. Then I wrapped it all up in plastic and secured it with some zip ties. All of this stuff I had just lying around. Honestly, I used to laugh at the amount of crap my dad kept in the shed back home, but now I am basically doing the same thing... the only difference is that I use said crap.

Hot water

There were a couple of choices to weigh up for a heating system. A propane boiler was at the top of my list until, in a moment of thought, my eyes were drawn to my heater running in the corner of the workshop (the same heater that blew out one of my electrical sockets in a shower of sparks just a few months ago), there was an aerosol can sitting on the counter just above it. That's when I considered the level of fire safety (or lacktherof) I have in my workshop, and thought I need a fire extinguisher, not a propane tank. so, a little research and I discovered handy little undersink water heaters, and this Redring 6L one was even under £100 with free delivery. I also included a fire extinguisher in that order.

Despite all the warnings about professional installation in the instruction manual, It turned out to be super easy to fit as well. It does help that it runs off of mains electric via a plug, so no wiring is required.
  • 1.7m of 12mm flexible pipe: the 1.7 must be measured between the cold feed of the heater and the closest non return valve on the cold water feed (Or an accumulator can be installed instead) This is to protect the unit if its holding water in the pipes, if the water gets too cold and expands, then it'll damage it unless the water has somewhere to go. the distance for my setup was a little shorter than 1.7m, so to save my having to install a second expensive accumulator, I took the pipe on an adventure around the wall to make it longer than 1.7m.
  • Pressure relief valve installed on the cold feed: The max pressure this heater can take is 6bar, so the pressure relief limits the bars of pressure as it enters the system. my pump doesn't produce more than 6bars anyway, but the instructions said that it MUST be installed, so like anyone who doesn't know what they're doing, I installed it because it said so.
  • Tundish: Prevents cross contamination from the wastes, and also provides an air gap so you can see if water is flowing from the pressure release valve.
  • Straight tap connectors: I used straight tap connectors to connect the pipe to the heater because they have little rubber washers in them, so when they're tightened onto the connectors, they are also sealed.  The JG female push fit could have been fixed directly to the connector without all the extra copper pipe and compression fittings, however I wanted to add a bit more pipe onto the cold feed to get the pipe length to over 1.7m.
  • Copper pipes on the hot feed to the faucet: Water coming out of the heater is understandably hot, so the pipes need to be able to handle high temperatures. Copper pipe and fittings can get a bit expensive for smaller jobs as you have to buy so much when going to screwfix or toolsation and you end up with a lot unused, but fortunately that was my situation when I installed an electric shower a few months ago, so I had a lot of spares (my house is basically a hardware store).
  • Flexi hose tap connectors: These came with the faucet, they're really handy because you don't have to worry about piping around at awkward angles or getting the length exactly right. 


Finally, the most important and legislated part of the setup, water wastes! letting used water just run straight out of my workshop and into the soil is a big no, even water used for hand washing must be dispensed into the sewage drain system because some soaps can contaminate the soil and that contamination can spread further into the environment. Unfortunately I have no direct access to the sewage drains in the workshop, so with my small budget my only option is a under-sink Jerry can to carry over to the drain as and when needed.

Overall: I'm happy with my little setup. It was a fun educational project and it's so nice to have quick access to water! The only down side is the heater takes a little time to get going as I don't want it on all the time, so I need to pre-heat the water when I want it.

If I'd build it from scratch with parts I could freely pick rather than use ones I had lying around, I probably could have done a better job, yes, but that's looking at it with the knowledge I gained from doing the project in the first place. So, I hope publishing this might help anyone else trying to do a similar setup, or at least provide some entertainment for anyone more knowledgeable. 

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