have you thought of using a ro ?
i use one to feed into a static 1000 ltr ibc,
tap water is 290 plus , or brings it down to 004 , resin lasts ages,
at 98 tds ,you prob would not need resin, or if you use it would last ages, saving you a load in resin.
another benifit is the water in my van tank is allways 000, so no need to worry about it going up whilst working
d