Folge Regenexperte auf Twitter

Greywater Recycling and Reuse

What is greywater?


Greywater is all wastewater that is discharged from a house, excluding blackwater (toilet water). This includes water from showers, bathtubs, sinks, kitchen, dishwashers, laundry tubs, and washing machines (Figure 1). It commonly contains soap, shampoo, toothpaste, food scraps, cooking oils, detergents and hair. Greywater makes up the largest proportion of the total wastewater flow from households in terms of volume. Typically, 50-80% of the household wastewater is greywater. If a composting toilet is also used, then 100% of the household wastewater is greywater.

Not all greywater is equally "grey". Kitchen sink water laden with food solids and laundry water that has been used to wash diapers are more heavily contaminated than greywater from showers and bathroom sinks. Therefore, different greywater flows may require different treatment methods that would render the water suitable for reuse.

Why greywater recycling?

The main purpose of greywater recycling is to substitute the precious drinking water in applications which do not require drinking water quality. Non-potable reuse applications include industrial, irrigation, toilet flushing and laundry washing dependent on the technologies utilised in the treatment process. With greywater recycling, it is possible to reduce the amounts of fresh water consumption as well as wastewater production, in addition to reducing the water bills. If greywater is regarded as an additional water source, an increased supply for irrigation water can be ensured which will in turn lead to an increase in agricultural productivity. 

read more


Regulatory Guide „Greywater Recycling“ is completed

The fbr-Information Sheet H 201 ”Greywater recycling, planning fundamentals and operation information” has been published by the German Association for Rainwater Harvesting and Water Recycling (fbr) as the first and only regulatory guide to be published so far on this topic. fbr-Information Sheet H 201 documents the up-to-date standard of knowledge in this field and defines requirements for the planning, implementation, operation and maintenance that have been proved and tested in the practice. fbr-Information Sheet H201 is recommended for manufacturers, planners and interested individuals and it gives first information on the operation of greywater recycling plants. A complete version of the Information Sheet H 201 can be found here:

Sheet H201


Examples for Greywater systems in preparation