Hi Marguerite and all, We have very hard water here. At my garden water intake valve, we have installed an activated carbon (granular) filter cartridge to reduce the salt build up problems. The filters and housings we use are from Tek Supply. While I don’t run tests on the garden water, over the years I’ve seen no salt build up in either raised planters or pots. And I know I would since we have no softened water anywhere on the property. I’ve seen buildup in other situations here. This has been an inexpensive solution. I’ve heard of (and have seen) commercial growers who install huge reverse-osmosis systems for their propagation houses where the tiny plants are bathed almost continually in clean water and nutrients and where any build up would severely damage seedlings. It’s much more costly. Our home has a whole house filtration system that includes a prefilter for sediment and uses a three-stage carbon block system with additional R-O for drinking. In addition to the filtered water in the garden, I also sometimes use vinegar water (about a tsp or two a gallon) when hand watering cactus and succulents to reduce pH….as well as the regular fertilizers. . Pam Contact me privately if you need further information about Tek or our system. Pamela Slate P.O. Box 5316 Carefree AZ 85377