What is the most effective way for reducing the calcium level in water?

I am working as a Community Water Supply and Sanitation Officer in Salima, Malawi, Central Africa, I am responsible for rural water supply in my project area.

We are facing a problem of frequent pipe breakdowns in our Chipoka Gravity Fed scheme (GFS). The breakdowns are due to high levels of calcium in the water which accumulate in pipes, this accumulation further lead to blockages or intermittent flow of water. After some period of time the pipeline breaks down. 

Because of these frequent breakdown, the scheme is hardly in use.  Otherwise the scheme has potential to supply water throughout the year as we have perennial springs and rivers as a water source.

So I  seek for some ideas on how best we can reduce the calcium percentage in water in a sustainable way?

As said we are using gravity fed piped schemes and it is for domestic water supply.