Building my own compost toilet – part three (with video)

Remember that this article was originally written in 2013. Since then, some of my views and ideas will have changed, but the principle of building your own urine-diverting compost toilet still stands…

So in Part Two, I’d finished the compost toilet, but found the fan was quite noisy. In this final thrilling instalment (I know, I know, you can hardly contain your excitement!), I’ll show you how I addressed the noise issue and take stock of the general performance.

You can buy the Privy urine-diverter from the UK distributor, WooWoo Waterless Toilets.

A quiet revolution

With the original 80mm fan, I was experiencing buffeting because it was blowing into a 68mm hole (that was the diameter of the downpipes I used for ventilation).

I swapped to a 60mm fan and that addressed the buffeting, but highlighted the general noise of the fan (this particular model anyway), which in my view became intrusive.

I should say that I am very noise sensitive, so it’s possible that you might have a different overall view on the fan noise than me, but I did think there was scope for improvement in terms of how loud it was.

I did some research and found a ‘branded’ fan (made by Sanyo Denki) to replace than the unbranded units I have previously purchased from Maplin (a UK electronics and gadget shop that’s now gone out of business). 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 one I’d installed.

My concern was whether the reduction in noise came solely as a result of a lower RPM (in other words, the fan blades span more slowly), 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!).

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.

Because I insulated and lined my shed a few years before I built and installed this compost toilet, 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 inlet 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 new, quieter fan, 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 down to use the compost loo pretty much exclusively, although being realistic, I can see that my enthusiasm for doing this trip on a cold and wet winters day might dwindle in time.

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 urine-diverting toilet bowl 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, but the up side is that it’s so comfortable and warm on your bum compared to a regular loo 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 (details of this are in the video below).

Using the compost 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, gently illuminated by the 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 well!

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

Video

Here’s the video – remember it was made in 2012 so the business and website I had back then is no longer in operation, and the quality isn’t brilliant, but hey, I didn’t have a fancy iPhone or iPad back then (and yet, we still survived!)…