In the recent years, there has been an upsurge in the sale of bulk water extracted from boreholes in most of Harare’s residential areas. Large numbers of water delivery trucks would be seen busy delivering water to various households while some large companies had also resorted to buying water from these water dealers to meet their production requirements.
While trucked water filled some gaps that had emerged following the erratic water supplies from the City Council, this business brought with it some complex issues which the Zimbabwe National Water Authority (ZINWA) moved in to address by banning the abstraction of bulk water from Harare’s residential areas. While ZINWA appreciated the role these bulk water suppliers played in filling the supply gaps of the municipal system, the authority also found it prudent to intervene and take measures to protect this highly sensitive and finite ground water resource.
The major reason why ZINWA stepped in and imposed the ban was because most boreholes in the residential areas were drilled using permits for domestic boreholes and not the commercial activities which they are now being used for. Some of the boreholes were even drilled without the requisite authority required in terms of Section 35 of the Water Act (Chap 20:24). For the avoidance of doubt the said section, which deals with the abstraction of ground water resources reads: “Before making an application for a permit in terms of subsection (1) of section 34 in respect of ground water for a purpose other than primary purposes, the written authority of the catchment council to sink, alter or deepen a well or borehole shall first be obtained.
In terms of section 43 of the same Act, the abstraction from such boreholes must be metered with proper abstraction records being kept and made available for inspection on demand by ZINWA.
Most of the boreholes in residential areas were therefore drilled to provide water for primary purposes, which the bulk water business operators were now departing from. Most of them seemed unaware or unconcerned with the adverse effects of their activities on other residents, the water table and the environment.
Excessive abstraction of ground water leads to the lowering of the water table. The lowering of the water table would affect all the people in a particular area, including those not involved in the bulk water business. This saw some people reporting drying boreholes while others were forced to fork out more financial resources as they had to deepen their boreholes to reach the lowered water table.
The other major reason why the bulk water operators had to be stopped was because of the adverse impact of over abstraction of groundwater or surface water. There is more interaction between the water in the lakes, rivers and streams and groundwater than most people think. Some and often a great deal of the water flowing in rivers, comes from seepage of groundwater into the streambed. Groundwater contributes to streams in most climatic settings though the proportions vary according to geography and geology. Excessive groundwater pumping therefore can alter how water moves between an aquifer and a stream, lake or wetland either by intercepting groundwater inflows that discharge into surface water bodies under natural conditions or by increasing the rate of water movement from the surface water body into an aquifer.
This might also have the net effect of lowering the water levels to a depth below what streamside or wetland vegetation needs to survive. The overall effect of this is the loss of riparian vegetation and wildlife habitat.
Uncontrolled groundwater abstraction also leads to the deterioration of the quality of fresh groundwater. Abstracting excessive volumes results in what is regarded as a cone of depression around the boreholes which might see poor quality water flowing into the cone of depression and therefore into the aquifer.
Land subsidence is also another reason why it was seen prudent to ban bulk water abstraction in residential areas. Land subsidence occurs when large volumes of water are removed from the aquifer. In the process, the soils underground collapse. Land subsidence can lead to many problems, including changes in elevation, damage to structures such as storm water drains, sewer systems, roads, canals and bridges. Subsidence is also known for causing an increase in the potential for flooding.
It is therefore against this background that all bulk water operators are urged to fully comply with the ban as their activities pose a real and credible danger to human life and the entire environment.