Requests to builders around the area were eventually successful. We secured three of them in one go for one of the weekends and the work that they did was very fast and of very good quality. With everything ready in the second site of the water source e.g. bricks, cement the building of the dam took us only one weekend. The second source (2.3m x 2.5m) is slightly smaller than the first source (4m x 2.5m). An advantage of the second source is that its water never runs out, it has more supply of water than the first source which has a considerable decrease of water during the winter season.
Whilst building the second water source we had another group working on installing ball valves into the tanks. These floating valves help to regulate water flow into the tank. Once the tank gets full the ball is pushed up closing the valve to stop water from flowing into the tanks. This prevents overflow. And once the water level drops, the ball falls down allowing full access for water to flow into the tanks. Before the installation of these valves, we had assigned a family that lives near the tanks to open and close the valves attached to the pipes whenever there was an overflow or shortage. This was troublesome because the family would sometimes not be available or simply forget to do so and people would have no water. Also the valves on the pipes were susceptible to children playing with them because of exposure.
PS: Pictures will be posted soon!