Hi Moorthy!, Nice to meet ...

Hi Moorthy!, Nice to meet you.  Are you sure the clogging is due to TDS? Generally the clogging by TDS is due to the crystallization of calcium and magnesium salts in the internal walls of pipes and equipment.  If that is the problem the best easiest and cheapest way to overcome it is by installing a water softener (with an ion exchange resin) before the water entrance to the piping you want to protect.  But before that, you have to be sure that the clogging is not because of suspended solids because to use water softener method, the water must be perfectly clear with very low TSS, and if you are adding chlorine to the water you must do it after the water pass the resin. Another option is reverse osmosis but is much more expensive and you waste a lot of useful water in the process. I think use of chemicals is not a safe option at all, as you told they are using this water for day to day use. To determine the size of the water softener you have to analyze the water in order to know the real composition of the TDS and mostly the real amount of calcium and magnesium.