The joy of the true composting toilet is that the output from the toilet is compost. The waste has been transformed so that it is pleasant and safe to handle. The composting toilet does not separate solids from liquids, as the liquid is required to provide Nitrogen and keep the compost moist. If there is more urine going into the toilet than can be soaked up by the compost, excess liquid (called seep liquid or compost tea) drains onto the evaporation chamber and out of the unit. In electric Sun Mar units the evaporation chamber is heated so that most of the liquid is evaporated off so that the toilet can have zero liquid discharge. The power consumption of the heating element can run into the hundreds on an annual basis which does not sit well with the most environmentally friendly customers. So install the non electric version? The problem with this in our climate in Northern Europe, especially in winter, is that  not enough evaporation cannot occur naturally so we get more seep liquid than we want.

One potential solution to the problem of excess liquid is to use a non electric composting toilet (Excel NE or Centrex NE) and also install the Pee 1000 unisex waterless urinal. Introduced by Separett as an accessory to the incinerating toilet (essentially to save power for ‘urination only’ visits) the product is useful along side a composting toilet also. The PEE urinal will take all the ‘urination only’ visits and so the composting toilet will get solids and enough urine from these visits to keep the compost moist. The non electric Sun Mar units are rated for one less person that the electric version so by adding the PEE to the system you can achieve the same capacity in persons as the electric equivalent with almost no running costs. Although the initial outlay of the Sun Mar and the PEE combined is slightly more, the electricity running costs are almost zero so you achieve payback in 2 years. Contact us for prices and the calculation spreadsheet to prove payback.

A couple of extra points to consider are (i) space; do you have the space in the bathroom for the urinal as well as the toilet and (ii) temperature; with the electric composting toilet version the heating element provides background heat to maintain composting (above 13C). With the non electric it is especially important that the room is heated and well insulated to keep the compost bacteria warm as composting ceases below 13C.

The ‘combination system’ is especially effective in applications where there are more females using the toilet as many males who have composting toilets can pee elsewhere depending on whether the compost needs the moisture or not. I hope this makes sense. Please contact us for more information.

Patrick Boylan (B.Sc)

Toilet Revolution