DIY Compost Toilet Installation – Part 3 (with video)

This doesn’t just work, it works brilliantly!

As I write this, it’s been over six weeks since the DIY compost loo became operational, so I feel it’s a good time to take stock and tell you how it’s been performing.

A Quiet Revolution

In the part 2, I recounted the problems of buffeting from using an 80mm fan, blowing into a 68mm hole. A 60mm fan sorted out the problem, but highlighted the noise of the fan (this particular model anyway), which in my view became obtrusive. I did some research and found a ‘branded’ fan (Sanyo) to replace than the unbranded units I have previously purchased from Maplin. It was advertised as a ‘silent’ fan, although the decibel rating showed it clearly wasn’t silent, but it would be quieter than the earlier units.

My concern was whether the reduction in noise came solely from a lower RPM, which might not move enough air to enable the toilet to perform correctly! Anyway, I took the gamble and ordered the fan. It arrived and was easily fitted in place of the previous 60mm unit. I was pleased that the wires seemed more sturdy, which made the electrical connection quite straightforward.

The moment of truth came and I turned it on. Good news, it really was a lot quieter and although the fan speed was slightly lower, most of the noise reduction seems to be achieved through better design and components (note to self, if you buy cheap parts, expect appropriate performance!).

…if you buy cheap parts, expect appropriate performance!

Most of the noise is in fact echoes of air movement through the vent pipe – changing the vent pipe arrangement can make a difference to the noise – experiment and see what works best for you.

Since then, we now sell ‘silent’ 12v fans that come in a moulding that will directly connect to 68mm drainpipe. You can find them in our shop here: 12V Silent Fan.

Because I insulated and lined my shed a few years ago, it is quite air tight and I was concerned that there was not a good flow of fresh air into the shed. Without a fresh air coming in, the fan would be working harder than it should be and the whole system would not be working at its best efficiency – possibly reducing the life of the fan. To help with this, I fitted a small controllable air vent to the door of the shed.

Sprucing Things Up

The final thing I wanted to do with the compost toilet was to give it a coat of something to a) make it look prettier and b) give it some protection against spills.

I had some exterior garden furniture/shed paint in a cream colour, so used that. My throne now looks the part and is completely functional.

Six Weeks On…

Since I fitted the fan, six weeks ago (at the time of writing), I can report that I have only used the flushing toilet in the house once for a ‘solid’ deposit. Come rain or shine, I’ve trundled down to the shed to use the compost loo pretty much exclusively. I reckon this equates to saving around 650 litres of fresh, drinking quality water (if you’re on a water meter, this equates to around £4.20 of water assuming each flush is around 5 pence).

The main point to note is that there is no smell at all. In fact, the previous musty ‘shed’ smell that was there (probably because there was very little air movement in the shed) had also gone – in other words, fitting this toilet had actually improved the air quality in the shed!

I’d opted for the Separett Privy 500 toilet bowl kit which comes with a polystyrene type seat and lid (as opposed to the Privy 501 which has a ‘regular’ seat and lid). I was initially concerned about the durability of the seat material and thought that at some point, I would replace it with a standard loo seat. I still am slightly concerned about the long term durability of the Privy 500 seat – kids will undoubtedly pick at it over time, but the up side is that it’s so comfortable and warm on your bum compared to a regular loo seat! We’ll have to see how it stands up to the rigours of daily use, but if it does wear, I will be tempted to get a replacement polystyrene seat.

Although the toilet was fitted and working, I wanted a way of washing my hands in the shed. I had previously purchased a 2nd hand ‘Whale’ hand pump (the type often fitted to caravans and boats) from Ebay and fitted this onto the worktop in the shed. A length of hose goes from the bottom into a Jerry Can on the floor, which I periodically fill with water. A plastic bowl under the tap means I have hand washing facilities on tap. When done, I take the bowl and pour the dirty water into the urine part of the loo bowl – this will also help stop urine crystallising in the pipes and prevent any ‘latrine’ type smells.

Using the Toilet

As I mentioned above, the polystyrene seat makes using the loo on a cold November evening not as bad an experience as you might think. As I sit there on the loo, in my shed, under the warm LED lights powered by the 12 volt battery, charged from the solar panel, there is a degree of smugness that comes over me! This doesn’t just work, it works brilliantly!

This doesn’t just work, it works brilliantly!

There are a few different aspects that you have to get used to. Sitting on the loo, you feel a slight draft on your ‘undercarriage’ as the fan draws air into the loo – it’s not an entirely unpleasant experience, but probably one you’re not used to! When you’ve done your business and wiped your bum, the loo paper all goes into the solids hole and there’s no getting away from the fact that you are looking into a bucket of poo. I’m not entirely used to that yet, but I’m getting there!

When the Bucket is Full

The one thing I haven’t had to do yet is empty the solids bucket. After 6 weeks, I guess it’s nearly full – hard to tell exactly as the loo paper bulks it out a bit, but I might get another week before it needs changing. Separett say that the Villa 9000/9010 models will serve the average family for around 3 weeks before the bucket needs changing and my experience is pretty much in line with that.

I hope that my resolve holds out and I continue to use the compost loo over the regular loo throughout the winter and beyond. I’m sure that there will be times I’ll cave in (when it snows perhaps), but I’ll give periodic updates.

I think one of the main reasons this is so successful is the ventilation system (12 volt fan etc) which ensures absolutely no smells at all in the toilet area and accelerated drying of the solids in the bucket. In a future blog, I will look at alternatives such as using cover materials as several of my customers have opted to try this route first, so I can gather their feedback for your benefit. I fully appreciate that there may be times or places where you cannot fit any type of fan so we’ll look at alternatives and how effective they are.

I’ve made a short video showing the loo in place and discussing how it’s used etc.

Posted on 21 Comments

21 thoughts on “DIY Compost Toilet Installation – Part 3 (with video)

  1. Nice job, I did pretty much the same thing when I redesigned our old Sun-Mar composting toilet. A vertical vent stack with no bends it in may not require a fan at all. Strictly speaking this is not a composting toilet but one could compost the waste once removed from the toilet.

    1. Thanks for reading our blog and your comments. I agree that a vertical stack should work OK in most circumstances, depending on the vent cowl. Personally, if there was a little bit of smell, I wouldn’t mind, but in this instance, I wanted to create a ‘shining example’ and so the fan guarantees a pleasant experience, and I had 12 volts in the shed already, so no brainer! You can also help with odours by adding the odd handful of sawdust or other suitable cover material.

  2. […] ← Installing a Separett Villa 9000 composting toilet DIY Compost Toilet Installation – Part 3 (with video) → […]

  3. As you had access to the toilet from the side, is there any reason why you didn’t decide to just hinge it at the front after the discovery of the problem with version one? It’s just that, it seems to me that would be the way which created least movement of the wet conection.

    1. Hi Glen – if the structure was slightly higher, side access on the Mk 1 unit would have worked, and as you say, would have meant little or no movement for the wet connection, which is good. The problem I have was that I designed the toilet to be as low as possible and hence there were parts of the toilet bowl (where the solids drop through) that sit very slightly inside the solids bucket, meaning you could not slide the bucket out without it fouling the bottom of the bowl – it would need to be tipped slightly, which is not ideal. If the box was much taller, you would need to consider making a footstool/rest as it might be uncomfortable for people with shorter legs.

      Another alternative would have been to find a shorter bucket for the waste, but in the end, I was still unhappy with some of the wasted space front to back as I could re-use most of the wood, I thought it better to make a unit that was ‘right’ for me. Doing it again, I would also not be so fixated on making the top hinge (which led to issues of alignment between the bowl and the urine pipe) – instead, just lifting off would be fine.

      In a strange way, making mistakes is all part of the learning process and teaches invaluable lessons – although if I’d spent a little more time at the design/drawing board stage, I might not have made them!

      Are you planning to make a unit like this?

  4. We have a loveable loo and a shed near our pool with no electricity. I was wondering your opinion of using it for pee only so we would not have to drip all over to use the indoor toilet. How often do you have to dump it and where if it’s pee only? And would it become a scary thing in the off months with critters?

    1. Hi Naomi. Most of the loos we sell are urine separating, so the pee goes into a soakaway in the ground (basically a hole filled with gravel). Because pee is not classed as a pollutant (in most cases) and is sterile, letting it go into the ground is not usually an issue as long as you have free draining soil and are not too close to a water course – regulations may be different in the USA, but here in the UK you have to be 15 metres away from a watercourse.

      I’ve not dealt with a situation of collecting only urine, so I can’t offer any experience – if you want to look at collecting pee only and the best way of dealing with it, I suggest you read the book ‘Liquid Gold’ which has lots of information. Hope that helps!

    2. A further thought – if you stick with the ‘loveable loo’ just make sure you place a lid on the bucket when it’s not being used for any length of time, and/or empty it & clean the bucket – that should keep everything contained in the bucket and hopefully won’t attract critters.

      1. Thanks! Very helpful.

  5. I also use chopped hemp/cat litter and wood shavings smells OK too. Just remember the bigger the bucket the heavier it will get when its time to empty or replace it.

    1. Thank you for sharing your experience Charles. I tried not using the fan and adding wood shavings – personally I found this struggled with odour control as you really need something finer. Shavings mixed with sawdust, or the chopped hemp etc might work – try whatever you have on hand! It did however mean I was able to switch the fan off at times (which saves electricity, particularly precious in winter when the solar panel doesn’t receive much sunlight) – I made sure the fan was on for 30 mins or so after each ‘solid’ deposit and that worked OK.

  6. Here an idea is: to set an auxiliary fan in the lid above the center of the bucket so the air flow would be direct to the bucket. It seems to me it would help dry the ‘solids’ more efficient and give significant reduction of the ‘solids’. Such function in the Separett Weekend (Villa 9000 / 9010) does not work properly because of inappropriate position of fan. This fun would be switched on-off by reed switch with magnet (that can detect horizontal-vertical position).

    1. Hi – it’s a good idea, but my concern is that it adds a layer of complexity to the product, making it more expensive and more liable to breakdown. What I really like about Separett products is their approach is a very simple one with the minimum of moving parts. The fan in the Separett Villa etc is primarily there to remove odours (which it does perfectly, as customers will tell) – a secondary effect of this is that by drawing air over the top of the solids container, you create a lower pressure in the container, which will help wick moisture out. Separett do not claim to dry the solids, but rather ‘help’ to dry them, with the main composting etc taking place outside the toilet in the compost heap.

      The other concern I would have with a second fan which blows in, is balancing the force of the fan against the extraction fan. Too much air flow in means the other fan might not be able to remove the air quick enough which means it would probably leak out into the room, bringing odours with it. I’m sure it would be possible to create a set-up as you describe, but apart from slightly reducing the volume of solids, I’m struggling to see the benefit of adding complexity to a system that already works well (from the point of view of odour removal).

      Anyway – very good to hear your thoughts and thank you for sharing them!

  7. Hi Martin. I am just making a composting loo for my workshop from scratch but rather than buying any parts I have raised the floor about 16 inches for a sealed solids container with a fan and vent in the lid. I have made a pottery urine collector attached to an old chimney pot which is a perfect loo height..the urine was going to go into a bottle but reading your article It will now go into a soakaway. It will be “going live” in about a week. Can you forsee any problems? My main concern is treating of the solids when emptying as I dont have a compost heap. Pete.

    1. Hi Pete. I’m not entirely understanding how your solids container will work or be accessed for emptying? The solids will need to be composted in some way to make them both safe and pleasant to use/work with. This ‘secondary’ composting (some ‘primary’ composting will start to take place inside the loo) can be done in a regular compost heap, or preferably a compost bin. If large bins are not available or simply not an option, smaller plastic containers to which air can get in/out, along with regular mixing of the contents will also work. Best wishes, Martin

  8. Thanks for all this information. I have just finished building my own toilet using the privy 500 and ended up with a similar design to yours. I am not having any problems with it so far but my girlfriend is having problems aiming in to the correct sections. Have you experienced any problems with women using the privy 500? For example pee missing the urine funnel and going in the poop bucket or vice versa?

    1. Hi Karl. Thanks for your comments. When females first use a urine separating toilet, getting the right position can take a few goes – my wife did exactly the same when I first built my compost toilet! We recommend that females sit a little forward (than usual) to urinate and move a little further back to poo. I always add a good layer of wood shavings or other soak material to the solids container to absorb any urine that gets in. People tend to figure it out quite quickly, but newbies can be thrown!

      1. Thanks for the quick reply. She will be pleased to know it is not just her who experienced this 🙂 I’m pleased to know it wasn’t a result of my poor construction skills. Thanks for the help.

  9. Martin, I’m going to be building something similar in an extension that is just beginning construction. The floors aren’t in place yet, so I have the opportunity to build in pipes underground as needed. The toilet will be against an INTERNAL wall, so my plan is to run the urine pipe down below floor level, then turn 90 degrees and run under the floor until it gets outside, where it can go into an appropriate soakaway etc.
    My question is, can I do the same with the vent pipe, putting a fan in the pipe to push air out?

    1. Hi Mike. In principle yes. You need to be aware that of the issues that will reduce the efficiency of the fan, namely the length of the pipe and the number of bends/obstructions. It might be feasible to use flexible pipe (such as the type used in dust extractors for woodworking machinery) which reduces the sharp bends. Also might be worth considering have a more powerful fan at the exit point rather than in the toilet itself (where a powerful fan might be noisy?). It all depends on the pipe lengths needed.

  10. Your posts have not only been extremely insightful and helpful, but also good for several laughs in your manner of storytelling – thank you for sharing! I found it very relatable to the feeling in “part 2” of wanting to give up and then deciding it’d be cheating… and the feelings of finally being victorious! “This doesn’t just work, it works brilliantly!”–I love it!! Thank you for sharing so much valuable information for those of us trying to get started with composting loos. Cheers!

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