There are three ways to reduce hardness in water: diluting the current water with rain water, reverse osmosis (r/o) water or distillation.
Rain water is great if you get clean rain or any rain but it's usually seasonal and can't always be relied on to be there when you need it. So you have to store lots of it and keep it on hand. Clean pure rain water should have a pH of 7.0, and a GH and KH of 0ppm.
Reverse osmosis (r/o) water can be expensive to buy and most people get a reverse osmosis unit for home use. R/O units come in different grades and the good ones have a 1:1 ratio whereby they produce 1 litre of pure water and 1 litre of waste water. Lower quality units have a 1:2, 1:3, 1:4 ratio where they produce 1 litre of pure water and 2, 3, 4 or more litres of waste water. This can increase your water bill if you are wasting 200 or 300 litres of water just to get 100 litres of pure water. So check the packaging and find a good quality unit. The waste water has all the minerals and some chemicals in and can go on the lawn. Good quality r/o units will provide water with a pH of 7.0, and a GH and KH of 0ppm. lower quality units will give water that has some minerals in but it should be less than 20ppm GH and KH. As r/o units get used their filters get clogged up and need replacing. When this happens you start getting a lot more minerals in the pure water.
Distillation is good if you live in a sunny area but not so good in cold climates. You can buy electric stills, make one that runs off fire like the old moonshiners used to do, or make a solar powered still. Distillation is slower than r/o but you don't waste any water.
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SOLAR STILL
Get a large plastic storage container and put it outside in the sun.
Pour a bucket of water into the storage container.
Put a clean bucket in the middle of the storage container. Have a clean, non-porous rock in the bucket to stop it floating around.
Put the lid on the storage container.
Put a rock or small weight on the lid in the middle, so the lid sags above the bucket.
As the sun heats up the container, water will evaporate and condense on the underside of the lid. The water will run towards the centre and drip into the bucket. When the bucket is full of water, you put it into a holding container and put the bucket back in the storage container with another bucket of tap water.
You get pure water with a pH of 7.0, 0 GH, 0KH and no wasted water, no power used and it's cheap to set up. The drawback is it needs sunlight. You can do it on a much slower scale inside a warm house but it is a lot slower and relies on the warm air in the house causing the water to evaporate and not the sun.
