i've been told that it's very bad to use the water from my clothes dryer to water my plants. Is this true? It seems such a waste. Also, is it Ok to use water that goes through a water softener on plants? My African Violets didn't seem to like it.
No, it is not true. The water from your dryer is very similar to rain water as it is simply condensed water vapour. However just like rain water it is slightly acidic (from C02 in the atmosphere which dissolves to form carbonic acid) so avoid using it on any plants which need alkaline conditions. Basically if it is recommended to avoid using rain water on any particular plant then don't use dryer condensate or softened water.
Water via a water softener contains salt in some cases. Too much salt is bad for many plants except those who like coastal conditions. I can only assume the advice given too you about water from a dryer is based on the fact man made chemical residues, which adheres to clothes even after rinsing, will be bad for your plants.
The accepted wisdom is to rely on rain water for some plants, if not all. Tap water still contains traces of fluoride in many area's and trace amounts of other chemicals used in treating water supplies.
Dryer water will contain elements from the washing soap no matter how you rinse it.
Our water in the Teesside area is soft water (kettles never fur} and contains fluoride I use it on plants when the rain water butts are empty with no dire results and I still have all but one of my teeth. A lot of nonsense is talked about what is in our water, where ever you live the water will have some additives from the natural rock, the reason we get hard or soft water depends on where it lands as rain. If you ever drank water that had been through a water softening plant for boilers you would think it totally tasteless, it will not even make a cup of tea. We need additives and minerals we get in water and so do plants.
If I had water from a source I wasn't sure of I'd use it for shrubs, (including fruit bushes), and established perennials rather than leaf crops or seedlings.
I haven't got a clothes dryer so I haven't had to consider that one
I've been pouring mine on the nearest plants in my garden all summer - happen to be a camellia and a pieris and they are fine. I figured it would be similar to rainwater. These are acid-lovers so don't know how other plants would fare