Svenska | English | España



Greywater is bath- dish- and wash-water. It breaks down much faster than waste water containing toilet waste and it has only 1/10 the amount of nitrogen. It can become an excellent source of irrigation.

Here we show two alternatives. One is very simple and effective way using a covered irrigation trench, relying on the soil and its organisms to treat the water.

Irrigation ditches are simple and reliable to operate. They can be constructed with cementboards for both walls and and tops. (the commercial name is Cetris board). Greywater is simply pumped or gravity drained into the ditches from a dosing chamber. Once in the ditch and on the ground the organics is slowly decomposing aided by both micro and macro organisms.

The top cover becomes the walkway between the plant-rows. For inspection or maintenance the top covers are easy to lift off. A distribution plate is placed under the pipe exit to avoid for the water to errode the area where the water lands. Food residues and fat from the kitchen discharge will build a successive clogging mat but will also be consumed by earth worms and Sowbugs etc. Hash cleaning chemicals containing chloride and Fluorides should be avoided at least not flushed down the sinks.

The second proposal is more for permanent construction with more conventional elements but is a design for greywater and allows for much less maintenance than if toilet waste is mixed in. Sludge can be removed every four years instead of everyyear.

Yearly maintenance is usually required by law when a septic tank is installed for sludge and grease removal. A septic tank needs to be accessible by a sucktion truck. If good infiltration soil is not available, as can often be the case in the archipelago or on steep building lots, the greywater can be pretreated as shown below and as the final treatment be used in planterbeds, sometimes terraced, as part of the landscaping. The plants receive both irrigation and fertilization by this method.

For more information in english, go to or click here.


Based on 45 years experience


Carl Lindström is a civ. egineer from KTH Stockholm and MIT Cambridge MA. He is the co-founder along with his parents of the first commercial composting toilet Clivus AB, which later became Clivus Multrum AB. There was an early assumtion that the system would produce solid compost to be collected in a collection chamber -- this never happened in reality. Over the years a new process has emerged called Long-Term Composting where the end-product is liquid and the solids is left for several decades. Based on decades of observations, a next generation process-tanks have been developed, taking less space and working with less maintenance and service than the older Clivus tanks. Carl was in the 1970ies working for the Swedish Environ-mental Protection Board and later served as the environmental attché at the swedish embassy in Wash. DC. He works now as earlier with the US corporation Clivus Multrum USA Inc. In 2007 Carl founded CompostEra AB in Sweden with sights set on solving waste problems in the Swedish archipelago, replacing the older latrine-collection systems. The new tanks are dimensioned to go for 30-50 years without solids-removal. Long-Term Composting has found great support in countries where ground water is vulnerable to pollution from toilet-systems that do not stop disease organisms from spreading into the environent. Subscribe to updates

© Copyright 2009 CompostEra | All rights reserved.
Tel: 08-770 15 30 | E-post: