We have used our SPT dishwasher now for about seven and a half years. I purchased it from a grad student at CSU to fit in the corner of our rustic kitchen. After a few years the inlet valve broke but I fixed it with an inexpensive part.
Lately the calcium buildup in the dishwasher has been accelerating. I reduced the circulation time for the Mangox filter to save water. We were using 600 gallons a week and now it uses 300. But that meant build up in the dishwasher more frequently.
In order to address the problem without treating all our water, I purchased an RV water softener for just the dishwasher.
The first step was hooking the unit up to a faucet to run the water until clear. It’s cold outside and I could not use the outside hose faucet to easily connect it so this took me awhile. I had just purchased a set of faucet adapters for a small washing machine hookup. So I dug through those to find the right combination to make the connections. I tried the washing machine hose but it leaked profusely at the elbow no matter how hard I tightened it. So I used the hose that came with the softener and an old washing machine hose on the other end. Neither leaked.
After prepping it I was ready to install it on the dishwasher. The unit is 10 3/4” wide.
The dishwasher fits under the sink cabinet but in the corner so there was enough room for the softener behind it. This is a portable dishwasher originally set up to connect to a sink but I had altered that with pex and pex sharkbite connectors. I reduced the 3/4” hose connections with hose to 1/2” FPT connectors that I had already and purchased two 1/2 MPT to pex connectors. I have leftover pex pipe so I used most of the existing pipe to connect to the softener and cut a new piece for the line to the dishwasher.
I was able to push the softener all the way back into the corner. I left enough pipe so the dishwasher can be pulled out any time.
The softener came with test strips and I confirmed that it was working by running a rinse cycle and pausing it to test the water. It tested at the bottom on the scale.
The softener claims it’s good for 2000 gallons in the ad but the directions are more conservative. They explain that it depends on the hardness of the water going in. In our case the water delivered to the softener is at 250 ppm on the test chart. The equivalent grains per gallon is about 15. The 16,000 grain capacity is divided by this hardness measure to determine that the unit should soften just over 1000 gallons before it needs regeneration.
The dishwasher uses 4.25 gallons. If we run it every day, though it’s more usual to run it every other day, it should soften for about eight to sixteen months. We can use a test strip every couple of months just to check.
It is recharged with two boxes of table salt. Then it has to run for 20 minutes at low flow and 10 minutes at full flow to flush the system. I can disconnect the sharkbite and run it into the kitchen sink. Once a year it should be back flushed which means disconnecting it and hooking the supply hose to the output. Then it flushes backwards for 5-10 minutes. Also the case should be tapped on the floor to move the resin back to the bottom of the tank. I might as well recharge and back flush about the same time each year. If I do this in summer I can just attach it to the outside spigot.
It’s extra maintenance but worth it to have the dishes get clean and keep the dishwasher from clogging and breaking.