Should softened water be used for watering indoor plants?

When using hard or soft water to water houseplants, it should be remembered that both contain minerals which will be deposited in the soil. If allowed to accumulate, plant growth will not necessarily be sustained. Rain, distilled or deionised water is preferable. Hard water is the second choice and softened water an inadequate third choice. Only a few plants take to artificially softened water in the long term although it is unlikely that any positive harm will result. Watering the garden with softened water can be very wasteful, unnecessary and expensive. We advise that all outside taps used for garden watering be left connected directly to the incoming hard water main.