Recommended maximum sulphate ...

Recommended maximum sulphate levels in drinking water is generally 250 mg/L.  Levels above this can be tolerated; however, if you are not used to drinking water with elevated sulphate concentrations you can overstimulate some bacteria in your intestine and it can be painful.  Infant formula should not use water with greater than 500 mg/L.  Ion exchange and reverse osmosis can remove sulphate.  Reverse osmosis requires extremely high pressure, so I doubt point-of-use (at the tap) household RO treatment systems achieve RO treatment.  If you buy one, make sure it has been NSF tested and certified for sulphate removal.  Ion exchange involves adsorbing sulphate and typically releasing sodium, plus you will need to regenerate the IO resin once it’s absorptive capacity has been reached.  Both technologies will generate a brine waste stream with elevated sulphate concentrations.  Sulphur is an essential nutrient in crop production and extremely high concentrations of sulphate are applied to large crops in the form of ammonium sulphate - so you don’t have to worry about releasing the sulphate reject to the wetlands or other vegetative areas - or simply release it to ground.