1st International Conference on Rain Water Cistern Systems
Honolulu, Hawaii, USA - June 1982

Section 6: Related Topics

Page 348

Rain Water Cistern Systems in China

Jiaxiang Zheng
East China Normal University, China

Introduction

Rain catchment systems have long been used in China. People like to drink rain water because it is cleaner than river or well water and does not have the bad odor and taste of river or well water.

In the vast area south of the Yangtze where rainfall is abundant, rain water cistern systems have been a common means of water supply in past years.

The method of collecting and storing rain water was rather simple. The most available material that people used for making rain water gutters was mao bamboo, which is very common in South China and has a thick stem, which can be hallowed out and split into two halves for use as gutters. Since the introduction of tin plate and galvanized iron, people have liked to use them instead of bamboo for making gutter systems, although they are susceptible to rusting and are more expensive. Earthenware, a traditional material used for making vessels in China, is also available for making rain water cisterns. People use large earthenware vats as storage cisterns. The vats have various sizes, but the largest one has a volume of about one cubic meter. 'In appearance it is like a bowl, with an upper diameter of about one meter or more Although earthenware is fragile, it is an ideal material for a rain water cistern because it is less expensive and has no effect on water quality.

In rural areas of China, an ordinary household usually has a small yard where large earthen vats used as rain water cisterns are placed just under the gutter systems to receive the rain water from above. When it -rains and the vats are filled with water, wooden covers are put on them to avoid contamination and to shut out the sunlight to prevent algae growths. No filtering process is needed, but some alum as coagulant is generally added to remove the suspended solids. The impurities on the bottom of the vat should be regularly cleared away. Because mosquito larvae sometimes breed in the water, a goldfish is placed in the water to feed on them.

In China, an average peasant may have a commodious house with a total roof area of 50 to 100m². As a catchment area, it is broad enough to receive rain water for drinking, but still inadequate to provide water for other domestic uses. Thus, river or well. water must be used for washing and other domestic uses. Since the annual rainfall in subtropical and tropical areas of China generally exceeds 1 000 mm, and in many regions over 1 500 mm, most of the domestic demand for water can be very likely technically improved by using rain water cistern systems with larger catchment areas.

In recent years, tap water has become an increasingly common source of water in small cities and towns of China, while rain water cisterns have decreased. However, people do not like chlorinated water for drinking because of its odor, and some people still collect rain water for drinking.

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