If you collect rain water, it is necessary to collect in large vessels for stagnant water from a barrel is not suitable. The easiest method of softening tap water with filtration through household filters and subsequent boiling. But, here there are drawbacks. Not always recommended to water plants with this water as it is devoid of oxygen. But still, if other mitigation options for You is not available then water should boil.
You can also make the water softer by adding a special agent to neutralize the stiffness that you can buy in the store. After claim water for a few hours and drain the lower layer of this. The water is ready for irrigation. To mitigate may use chemicals containing acids, e.g., oxalic acid. However, for this You should know the water hardness and to calculate the dose.
One of the good ways to mitigate the carts, which is perfectly demonstrated in the home is the freezing of the water. The technique of the freeze is to various speeds of freezing water crystals and impurities of the salts contained in the water. Therefore, this process gives a positive result only with proper freezing. If you just freeze the water, all the salt will turn to ice, and thawing again mixed with water. Starting to freeze, follow the process. The salt will freeze last and when non-frozen liquid will remain low, drain it. Drained water and will represent a saturated saline solution, and melted ice – melt soft water. Otherwise, the freeze does not make sense.
For watering outdoor plants (for the room it will not do) the water can soften by adding 0.5 teaspoon of borax.
The best way to neutralize the hardness of the irrigation water is adding wood ash or fresh peat. To do this, add per liter 3 grams of wood ash. If using fresh peat, the proportion of 100 grams for 10 litres.