Today most buildings use chemical to treat the cooling towers, to kill bacteria and reduce water blow-down.  However, the use of chemicals increase concentration levels of dissolved minerals (especially calcium ion and magnesium ion) which lead to scale build-up in the piping system.  The scaling will lead to decreasing heat exchange efficiency. 

One of the most effective solutions today is to use DeCaIon electrolytic water treatment system, which improves energy efficiency (can be from 2% to 15%, depending on the state of maintenance of the entire chiller system), reduce water blowdown (typically around 60 to 80%) and remove chemical footprint.