Using standard 32mm rigid pipes on Separett toilets for urine diversion

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When you purchase a Separett Villa or Separett Tiny with Urine Extraction, you get a two metre length of semi-flexible pipe to lead the urine away (to a soak-away pit or other drain).

Separett Urine Hose

In many cases this is fine, but what if you want to use or connect to standard 32mm or even 40mm rigid waste pipe, as commonly found in the UK?

Why would you want to use rigid pipework for urine from a compost toilet?

Rigid pipework, whether ‘solvent weld’ or ‘push fit’ offers many advantages over the semi-flexible pipe supplied with your Separett waterless toilet:

  • Can be run over longer distances with ease, without ‘drooping’ between supports (which may allow urine to collect and increase the chances of blockages over time).
  • Can be connected to other standard fittings, for example if you are running the urine into an existing drain.
  • Lower costs of pipes and parts, compared to the Separett items.
  • Can be connected to larger diameter pipes, for example to avoid freezing if the a large part of the pipe is outside and the toilet is typically used in sub-zero external temperatures.
  • Greater range of colours – rigid pipes are commonly available in white, grey and black.

When 32mm is not always 32mm!

You would be forgiven for thinking that one 32mm pipe is the same as all the others, but you’d be wrong! In the UK, the stated size refers to the nominal internal bore of the pipe. The two common pipe fitting types of ‘push-fit’ and ‘solvent weld’ actually have slightly different external diameters (34.5mm for push fit and 36mm for solvent weld) and therefore, the fittings for ‘push-fit, won’t work on ‘solvent weld’.

There’s an additional layer to the confusion – the standards in Sweden (where the Separett products are designed and manufactured) are slightly different in that the given size refers to the actual external diameter, which is 32mm!

Thankfully, there is a way of connecting the Separett 32mm semi-flexible pipe to a compression coupler, and from there, you can use UK standard 32mm rigid pipe.

The process is slightly different between the Villa and the Tiny due to the access space and design at the back of the toilet, but the end result is the same – you can use standard 32mm push fit or solvent weld pipes.

The Adaptor

I’ve used a McAlpine S28 Straight Connector 32mm x 32mm, which you can get from Screwfix (amongst many other places). At the time of writing this article (May 2024, it was under £3.50). There are other brands (such as FloPlast) that will do a similar job.

The first thing to note is that the Separett semi-flexible urine pipe, can’t connect directly to this – the inner diameter is too small.

However, it will connect onto either the straight or angled connectors that Separett supply with their waterless toilets.

Rubber seal and blue pressure plate around the Separett straight urine pipe connector, ready to be inserted into the compression connector.
Separett urine pipe connector in place. The screw fitting (left) just needs tightening.
Separett angled urine pipe connector also works, as shown

Now you have one side connected to the Separett pipework, the other end can now be connected to standard UK 32mm.

Standard 32mm push fit pipe (left) connected to the McAlpine compression fitting (centre). Separett straight connector on the right.

Connecting to the Separett Villa

Due to the shape of the Villa, there is typically space to fit either the Separett straight or angled connector onto the pipe that comes out of the back of the Villa, and then fit the McAlpine straight connector (hint – fit the McAlpine connector onto the Separett connector, and then fit this onto the pipe on the back of the Villa).

This gives a neat solution that’s tucked out of the way under the rear overhang of the Villa.

32mm compression adaptor fitted to a Separett Villa with angled connector
McAlpine 32mm compression adaptor fitted to Separett angled connector on a Separett Villa

Connecting to the Separett Tiny

The Tiny is slightly more difficult because of the much smaller overhang at the back, and the proximity of the side and back of the toilet to the urine outlet point.

The easiest solution is to fit the standard Separett angled connector to the urine outlet on the back and have that pointing down or to the side, according to where you want to route the urine pipe. Connect a piece of the supplied Separett flexible pipe, long enough to get you either outside or to the side where there is enough space to fit the Separett straight connector, and onto that, the McAlpine compression connector, and then you are into standard UK pipe.

This is just one suggestion based on our own research and knowledge – there will be other solutions that might suit your installation better. Always test everything before fitting to ensure this solution works for you.

Other hints and tips for installing urine pipes

  • Use some silicone lubricant to make it easier to join the pipes and connectors.
  • When cutting pipes, remove the jagged edges on the inside and outside with some abrasive paper or a sharp knife.
  • Observe the minimal fall required of at least 1 in 10 along the pipe run. This allows urine to flow freely and quickly and will help prevent calcification in the pipes over time. The shallower the fall, the more slowly the contents will flow, increasing the likelihood of calcification.
  • Make sure the pipes are correctly supported to prevent sagging and movement of the joints over time.

If you need to purchase extra or replacement Separett urine pipe fittings, you can find them in our web store:

Separett 32mm Straight connector: buy in the web shop.

Separett 32mm Angled connector: buy in the web shop.

For details of various ways of dealing with the urine output from compost toilets, see our dealing with urine page.

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