The following shows what can be done in a semi-desert country where water shortages are frequent, and how rainwater catchment and storage can become an economic solution.

In April 1983 the drought in Botswana entered its third year. Lobatse, a small town with about 20,000 inhabitants situated 70 km south-west of the capital, Gaborone, is usually supplied with water from two nearby dams. The town is a "Waterworks Area" which means the supply is centralized and organized by the W.U.C. (Water Utilities Corporation). Although Lobatse has two groundwater basins, this water is not used in the central supply system. In April 1983 tight water consumption restrictions came into force, since both dams had dried up. The central supply system then received its water through a 70-km pipeline from Gaborone. The restrictions prohibited the use of water for gardening, car washing, swimming pools and even construction work. The only three institutions in town in possession of their own boreholes were the B.M.C. (Botswana Meat Commission), the Zimbabwe Railways (now Botswana Railways) and the Town Council. However all boreholes raised water that was considered not fit for human consumption. The Council borehole was linked to an irrigation system for the lawn in the stadium. Since the groundwater in Lobatse was not included in the restrictions, the Council was also allowed to irrigate the stadium lawn. This was very fortunate since the development of the stadium lawn and the maintenance of it until then had already cost a lot of money.

The major problems for the Town Council, however, were schools and clinics. At four primary schools, two clinics and one day care centre vegetable gardens were drying out. Traditionally, the diet of Botswana is carbohydrate-and protein-based. An extensive government programme made vegetable growing a compulsory educational subject for all primary schools. At the local clinics where special care is taken of children and their mothers, vegetables are grown and cooking is demonstrated. The big question was how all these activities could be maintained without sufficient water. Also, at the same time, hundreds of newly planted trees had to be watered. The Council owned two water trucks and after the stadium borehole had been provided with a standpipe, watering of trees was carried out with water trucks (bowzers). The schools and clinics were provided with old drums which had to be filled up once a day. The watering of trees worked because they were big enough to withstand short interruptions of the water supply without serious consequences. The supply for the four schools, two clinics and the day care centre was not satisfactory. A breakdown of a tractor could result in considerable problems. Since the borehole had to supply the stadium irrigation system and to fill all the bowzers, special arrangements for the staff had to be made. The first groups started working at 4 a.m. and bowzers were still on the road at 7 p.m. The bottleneck was the temporary storage of water in drums at the public buildings. The investment in drums became substantial since they were often stolen and had to be replaced. There was an obvious demand for better storage.

This resulted in the development of the dual system as it was then called. The dual system meant that rainwater reservoirs were built at the public buildings and always kept half filled with borehole water. When it rained the reservoirs filled up with rainwater, and when they became empty they were filled with two or four bowzerloads, depending on their size, and this could be timed properly. Early in 1986, all primary schools, the day care centre and the clinics were equipped with reservoirs and catchment systems. In addition a newly built community centre was equipped with a 59-m3 reservoir. Within three years and with only limited funds, an overall storage capacity of about 437 m³ was achieved (see Table 1).

Sizes of the reservoirs constructed differ due to the layout of the schools and the catchment possibilities. Only the Woodhall Community Centre, which was built in 1985, was designed according to the catchment needs.

Although tight water restrictions were lifted in 1985, the system remained in use unchanged. The reason was the tariff policy of the Water Utilities Corporation. Water in Lobatse is sold for a higher price than in other towns because the supply is very expensive.

The reason for not fixing a uniform tariff throughout all towns (W.U.C. supplies water in urban areas only) is to keep people aware of the more or less permanent shortage of water with emphasis on areas where the supply becomes very expensive. As a result of growing urbanization (Botswana's urbanization rate in the past was 11.2% per year, one of the highest in the world) more and more investment was necessary for well drilling, dam raising and pipeline construction. As shown in Table 2 water tariffs have been increased each year since 1982. The tariff is stepped up and the table calculated on the amount of 50 m³ and more. The tariff for the first 10 m³ is much lower but was also raised from 2.30 pula in 1982 to 5.20 pula in 1987. That is equivalent to an increase of 126% within just five years. However, prices for water consumption of 20.50 m³ and more increased much more. As the table shows, 50 m³ in 1982 cost 30.10 pula; the 1987 cost is 80.10 pula. This means an increase of 166% which is more than two and a half times the cost of five years ago. It could be argued that another tariff policy would be more justified. However, the system in use has definitely supported water saving and the rainwater reservoirs at public buildings in Lobatse become more and more economical. The costs of filling given in Table 1 are based on the sizes of the reservoirs, not on the consumption. It is unfortunately not possible to state an average amount of consumption since gardening is of different intensity and gardening areas vary. Refilling of all reservoirs is done three times a year if there has been no rain. This suggests a consumption of about 1,300 m³ equivalent to costs of 2,150 pula. This amount would still cover the construction Cost of a reinforced bricktank capacity of 21 m³ As the example shows, this dual systems is economically efficient. At the same time, the reservoirs are an ideal stand-by facility. Given the case that the centralized system may be temporarily not functioning, the cisterns could supply the population in the area of location. As all reservoirs are closed, a treatment with chlorine could make the water safe for use. Since it can be observed everywhere that the highest consumption of water is in areas where drinking water quality is not imperative, raw water should be used as much as possible.

Finally it should be mentioned that tree planting and keeping are not primarily decoration, but satisfy an environmental demand. Botswana is very much affected by soil erosion. The Government therefore directs that all support should be given to tree planting. An annual tree planting day enjoys public attention and nurseries are being founded in many places. Therefore, any water consumption restriction has a substantial effect on environmental conservation. Hence unconventional ways had to be found to continue environmental conservation while at the same time saving as much water as possible.