Using rainwater in dish washer ect

[John White]

Hello to every one in this group. I have been lurking for some time and finally I have a question that I would like to ask. Has any one in the group collected and used rainwater for use in a washing machine or dishwasher. If so how did it turn out. I am assuming that I will need a pump to lift the water from a butt to the inlet of the washer. If this is the case could I use some kind of pressure sensing switch so that the pump would run automatically when the washer demands water . Would the water need a great deal of filtering or can it be used right out of the butt. I ask this as I live in a very hard water area and I tend to get though a fair few heater elements.I think I am correct in saying that rain water would be nice and soft as it will have had no contact with the chalk downs that surround me. Thank you for taking time to read this JOHN

[Andrew Gabriel]

Connecting the pump to the washing machine inlet valve supply would be better (probably through a relay as these are often driven by low powered triacs or low current contacts).

You should filter it before it gets into the butt, or what's in the butt can go a bit manky. I have a downpipe connector for water butts which includes a gauze filter, but you do need to wash out regularly. It's also a good idea to let the water stand for at least an hour or two after any filling of the butt, which allows heavy dirt such as sand dust from roof tiles to sink to the bottom.

I live in a hard water area too, but I've never had a failed element. Are you doing lots of high temperature washes for some reason?

[Mike]

Try calgon or similar, when my washing machine packed up after 11 years service due to a fault in the controler, I took the element out and there was virtually no limescale. I live in a hard water area.

Mike

[Phil Anthropist]

Just some thoughts - no personal experience if this. How would you heat the rainwater or are you only thinking of a cold rainwater supply to the cold water inlet of a washing machine and dishwasher? If so, would the hot water inlets need blocking off so that the appliances no longer received hard hot water? For a cold rainwater-only supply you could consider a separate storage tank above the level of the appliances, with gravity feed, although the water pressure might be rather low. If the water pressure was adequate then the storage tank could be filled via a pump from the rainwater butt. I also live in a hard water area and find that using washing machine descaler every 3 months, and a boil wash once a month, cleans out the limescale. No experience of element failures due to limescale in 30 years, but we have spent a lot on kettle descaler! I regularly have to descale the steam iron - vinegar works well for that.

[Andrew Gabriel]

Most dishwashers don't have a hot feed. Firstly, they don't use enough water for the hot to have run through the pipework in most homes before they finish filling, and secondly, it's really only the final rinse that would benefit from a hot fill. For other rinses it's a waste, and hot water straight on to dirty plates will cook protein food matter making it much harder to wash off.

I live in hard water area too. Never descalled washing machine and never had any scale problems with it in 25 years. I wash at 35C mostly though, and it's 60C and above which will generate most scale. For the kettle I use a britta water filter, mainly because the tap water has so much chlorine in it, but it removes the hard water too. For steam iron, I use the condensate water from a dehumidifier and and air conditioner, which has no hardness in it.

[Mike]

Same with washing machines, when I looked around recently they were all cold feed only.

Mike

[Andrew Gabriel]

Reasons with washing machines are slightly different. Modern washing detergents must use a profiled temperature wash to work at their best, working up gradually from something like

30C to 45C to allow the various washing enzymes time to work at their optimum temperature before they are destroyed at higher temperatures. In order to ensure the initial fill is at no more than 30C, you either need a microcontroller based machine to mix hot and cold in the right proportions based on their temperatures, or you do cold fill only and heat electrically. Even when mixing, the amount of hot water required is again very small, often only just enough to make the water run hot at the end of the fill cycle, wasting all the dead leg heat in the pipework.

[Vodkajelly]

Will the water need to be cleaned with chemicals, if only because of the final rinse on the dishes?

Vinterestedj

[Phil Anthropist]

Well, in the process of trickling off the roof and along the gutters the rainwater will have come into contact with bird shit. So I would say yes.