With modern facilities, one can save up to 50% drinking water
The company Otto Graf GmbH from Teningen, founded more than 50 years ago, offers rainwater harvesting sys-tems for individual as well as industrial use, in many different sizes and designs.
As a result of increased water consumption in the last several years, water is becoming increasingly scarce. Even more significant, however, than the problem of quantity is the water quality. Due to more and more extensive contamination with harmful substances, phosphates, pesticides and other chemical substances, water treatment is becoming not mere-ly more difficult, but also more expensive. Statistics docu-ment that only one person (in Germany) uses, on average, 150 litres of valuable drinking water each day. However, for approximately 50% of uses, drinking-water quality is not im-perative, e.g. for flushing the toilet, operating the washing machine, irrigating gardens and parks, operating a car wash, etc. Especially for these purposes, the use of rainwater ena-bles savings of approx. 75 litres per person and per day.
In addition to cost savings, the use of rainwater involves ad-ditional advantages:
•it is free of charge
•it must not be pre-treated
•it offers protection from calcification of the washing machine
•it is an optimum medium for plants to absorb miner-als, etc.
The collected rainwater is channelled through a preliminary filter (e.g., a Graf Optimax filter) into the rainwater reservoir. This can be installed underground, or also above ground. From there, the water is carried with the aid of a pump via separately laid mains to the user stations. Should a drought occur, drinking water is supplied to the mains via an auto-matic replenishment system.
Although the filters typical to this market are equipped with fine strainer inserts, small dust particles do accumulate in the rainwater tank. These particles collect at the bottom of the tank to form a layer of sediment, and gradually convert to minerals. The sediment layer is absolutely significant to the water quality and should not be destroyed by re-suspension or too-frequent cleaning of the tanks. Therefore, the tank should only be cleaned every 10 to 15 years. Also, any con-cerns regarding the hygienic quality of the rainwater can be dispelled. In this regard, scientific studies have indicated that rainwater harvesting systems designed according to the latest insights warrant sufficient purification of the rainwater.