* Dam wall can be built onto rocks with slope of up to 15%, width of dam base must always be 3/5 of dam height, width of crest should be 30cm, special attention should be paid to the rock-wall base as this has potential for leakage, and the upstream side of the dam wall should be rendered with up to 30mm of mortar. Procedures for dam wall construction are given in certain guides.
* Phased construction might provide a manageable way for users to construct their own dams, whereby each dry season the dam is raised until experience shows that capacity is sufficient for water demand. In this case, start with a dam of 2 metres height, then build on it successively to a total of 5 metres in 3 more stages. The advantage of doing this is that you build according to enthusiasm and seeing how much water is stored.
====Water extraction====
For open water catchments, like from rock surfaces or stored behind earth dams, direct abstraction (using a pump or pipe) works well. Abstraction method should minimize disturbance of the settled water, thus reducing treatment requirements later.
* Direct abstraction is one option, via a bank-mounted pump ([[Small and efficient motor pumps]] or [[Handpumps]]) which uses a floating intake to reduce sediment intake. An outlet pipe and strainer through the dam wall to the downstream side is another option, but these have potential problems of weakening the dam wall. In addition, piping will have to be secured externally when traversing rocks, so care has to be taken to secure pipes with anchor posts.
* With preventive methods to reduce turbidity (silt trap, extraction method) the water is still turbid & contaminated and will require treatment.
* For direct abstraction, promotion of household water treatment is advocated. Choice of household water treatment technology should be based on efficiency of removing contaminants present in the water. For open water that may be prone to cyanobacterial blooms, a [[Concrete Biosand Filter]] is a good choice due to its ability to remove cyanobacterial toxins. Other technologies however may be more suitable for mobile communities (e.g. [[Sodis]] or a [[Ceramic pot filter]], depending on turbidity levels). For reservoirs near urban environments or where the runoff area has intensive agriculture practised in its vicinity, diversification of water resources is a good idea to provide alternatives for direct drinking purposes. Strengthening controls and restrictions on use of illegal substances will also help.
====Maintenance====
