Water Source Protection

Water source protection involves the protection of surface water sources (e.g. lakes, rivers, man made reservoirs) and groundwater sources (e.g. spring protection, dug well protection, and drilled well protection) to avoid water pollution (see also pathogens and contaminants).

While surface water sources and springs are directly exposed to human activities, groundwater sources are often protected through overlaying soil layers. However, accessing groundwater sources through dug or drilled wells allows contaminants to enter aquifers, polluting the well itself and the water in nearby lakes, rivers, or neighbouring wells, which consequently threatens both public health and the environment (MANCE n.y.).

In the past, the need for water source protection has often been neglected. As a consequence, many drinking water sources have become contaminated making water purification measures indispensible. The very slow flow of groundwater makes rehabilitation of contaminated aquifers both costly and time-intensive. While removal of pathogenic contamination through disinfection is more likely to be successful, some metals and chemical substances will permanently remain in the soil.

Recently, establishing adequate water source protection has been recognised as the most suitable and cost-effective method to keep contaminants out of drinking water and making costly water purification measures and construction of new wells unnecessary (GCC 2011; CONSERVATION ONTARIO 2009). This holds both for industrialised and developing countries.

Implementing water source protection requires a legal framework. This usually involves a protection plan, which formulates responsibilities, specific protection measures and basic rules that apply to all community members and water source users.

As many surface water sources are used for drinking water purposes, protection is vital. Generally, three basic strategies exist for protection (UNEP 2010).

• Prevention: No discharge of waste, pollutants or untreated water from domestic, industrial or agricultural use; optimised water use and practices in agriculture in order to stop nutrients from entering aquatic systems (e.g. establishing buffer zones).
• Treatment: treatment of polluted water prior to discharge; stormwater management: ensuring that run-off cannot transport pollutants into water bodies.
• Restore ecosystems: Enable or support natural rehabilitation processes.

Numerous simple preventative measures can be applied to protect springs, wells and aquifers from contamination. They are presented in the following five steps.

Step 1: Location / Site Selection of the Water Source - Never Close to Pollutant Sources

Before the drilling of a well or construction of a spring tapping starts, an appropriate site has to be found. Villagers or landowners are a good source of information and mostly point out a suitable location for them as users. However, several other important aspects have to be kept in mind when selecting the optimal site for a water source (WAL 2010).

A water point of any kind or source should be:

• Situated above the (seasonal) flood level of any nearby river or lake;
• In a location, which guarantees easy access for all water users all year round. This refers to physical access but also to legal access.
• In proximity to the actual point of water use;
• In an area allowing the rapid dispersal of spilt water;
• In a sunny area without shade to guarantee that the immediate well surroundings remain dry, so as to prevent bacteria, algae, etc. to evolve.
• In a location where the level of the water table is at a depth of at least two metres all year round (for wells);
• In distance from agricultural activities of any kind; particularly if pesticides or fertilisers are applied.
• In an area not susceptible to erosion;
• In safe distance to saltwater and any source of pollution such as a pit latrine, abattoir, dumping site, fertiliser or pesticide store, etc. (COLLINS 2000; WAL 2010).

The minimum distances to sources of pollution are given on the following table:

Step 2: Construction of Spring- and Well Protection

In order to protect contaminants from entering the spring, well and the aquifer through the water point itself, several specific measures can be applied:

Springs can be protected by installation of a spring tapping, a spring box and an adequate drainage system. Additionally, a surface water drainage ditch, dug above and around the spring area, diverts surface water run off from polluting the source. If the area around a spring intake is unstable or exposed to erosion, gabions or dry stone masonry can be used to stabilise the area (OXFAM 2008).

Drilled and dug wells need a proper sealing. First, an apron guarantees that no contaminants enter the well from the access point area. Second, an impermeable lining (for dug wells) or casing (for drilled wells) makes sure, that no close-to-surface-water laterally enters the well. As for springs, adequate drainage installations keep the immediate surroundings dry. After the completion of the well, a final disinfection with chlorine kills most pathogens that entered during construction.

The most decent construction of a spring taping, well lining, casing and apron is without effect, if pollutants are entering the aquifer in the mediate surroundings of the water point.

In a fenced, inner protection zone (with a radius of 10 – 20 m), all activities posing a risk of contamination are restricted (e.g. farming, grazing, firing, application of pesticides and fertilisers, construction of latrines, use of chemicals, etc.). It should only be planted with grass - all trees and bushes should be uprooted. Roots can damage the catchment by cracking the structures or by blocking the pipes. (MEULI & WEHRLE 2001).

Additionally, an extended protection zone (at least 100m in radius) should be put up. Its size depends on the depth and the type of the covering soil. The required radius thus increases if the spring catchment is close to the surface and if the soil is highly permeable (MEULI & WEHRLE 2001). E.g. if the soil mainly consists of rough sand and gravel, its permeability is rather high. The radius of the extended protection zone should then be extended to more than 150m. The area in this zone should be planted with mixed trees and bushes to prevent erosion and heavy run-off. The planting of trees that absorb large amounts of water (such as eucalyptus) is not recommended for the protection zone. Examples of more useful trees include cypress and pine. However, local varieties, which do not absorb large quantities of water, should be given priority. (MEULI & WEHRLE 2001).

Step 3: Fencing

Fences build around the water source precisely mark the inner protection zone and prevent animals from entering, defecating or destroying installations. Fencing is mainly applied for springs, as they are more susceptible to superficial contamination. However, shallow wells may also need protection zones. It is advisable to fence the inner protection zone with barbed wire and preferably to support the wire by planting a solid hedge of solid bushes around the fence (MEULI & WEHRLE 2001).

In many countries, groundwater protection zones are regulated institutionally. Specific rules define what kinds of activities are allowed in each of the protection zone levels (they may include more than two protection levels!). They can range up to several kilometres in diameter and allow everything between no activities and nearly all activities. In Switzerland, for example, the government has defined three levels of protection zones(WPO 1998):

• "S1 Wellhead protection zone: The zone S1 comprises the area immediately surrounding a groundwater well or artificial recharge facility (at least 10 m around the well and around the collection system). In this zone, only construction work and activities connected with drinking water supply are permitted. The aim is to prevent damage to the facilities or direct contamination of the water abstracted. The zone S1 should therefore be purchased and fenced in by the drinking water supplier.
• S2 Inner protection zone: The inner protection zone S2 is primarily designed to prevent contamination of drinking water with pathogenic microorganisms and to ensure that groundwater flows are not adversely affected or obstructed as they approach the well. In this zone, the spreading of liquid manure is therefore prohibited, as are the infiltration of wastewater and the construction of buildings and installations.
• S3 Outer protection zone: The outer protection zone is designed to ensure that, in the event of an accident, sufficient time and space are available to ward off any hazards to drinking water. Thus, facilities that pose a hazard to groundwater (e.g. petrol stations) are not allowed to be located in zone S3. Wastewater seepage and gravel extraction are likewise prohibited in this area.”

Step 4: Set up Rules for all Community Members

Any protection plan rises and falls with the behaviour of the community members, their attitude towards the plan and their knowledge. Besides the installation of constructional measures, simple rules should be set up and communicated by a local caretaker.

Such rules can include:

• Don’t defecate close to the well,
• Don’t let your animals graze close to the well,
• Don’t throw any garbage into the well, etc.

Step 5: Management of Operation and Maintenance

Only adequate operation by the water users and frequent maintenance by a local caretaker can ensure a safe long-term usability of the water point. Operation and maintenance activities are best organised through a local management plan.

The remit of a caretaker involves the:

• Inspection, cleaning and repair of spring installations and well (e.g. cracks in the apron, leaking parts, etc.)
• Monitoring activities in the surrounding area
• Up keeping the protection zone/ repair of the fence
• Checking for appropriate operation by users and providing health education(OXFAM 2008).
• Checking whether the basic rules are respected by the users

Step 6: Abandoned and Unused Wells

 Abandoned wells are wells that are no longer in use. Over the years, many wells around homes and farms have been abandoned without being properly sealed and decommissioned. Abandoned wells or improperly decommissioned wells can pose a serious threat to groundwater quality and can also be a safety hazard. Therefore, all abandoned wells should be properly plugged to prevent contamination and to eliminate any safety hazards. When a new water well has to be drilled, the old well should be plugged (MANCE n.y.). See MANCE (n.y.) to learn how to decommission and plug a well properly.

Abandoned wells:

• Can allow surface run off to directly enter an aquifer, contaminating the aquifer and potentially contaminating nearby wells;
• Can permit cross-contamination of different aquifers encountered by the well bore;
• Can be a physical safety threat, as they are often not marked or covered, and can pose a hazard to people or animals that might fall into them;
• Can be a liability problem if the well contaminates neighbouring wells, or if the abandoned well still exists at the time of property resale (MANCE n.y.).

Increasingly, water planners and communities are looking to source water protection as a key to improve water quality and lowering water purification costs. Focusing on the protection of the drinking water sources in order to reduce or eliminate the need for purification is a more sustainable approach than cleaning the water once it is polluted.

Protection measures are simple and can be constructed with locally available material by local people; consequently, costs are relatively low. Basic rules for community members can quickly be set up and communicated. The tricky part is keeping the water sources well maintained and making sure that people respect the basic rules that come with the measures.

Also, healthy, resilient ecosystems help to purify water, regulate the water cycle, and thereby degrade many contaminants before they enter and pollute water sources (UNEP 2010).

All in all, water source protection keeps contaminants out of drinking water and is often more cost-effective than removing contaminants after the water source has been polluted (GCC 2011).