I know that some of you will explode at the thought of a dishwasher being used in a sustainable home but by putting one in I can convince the client/wife to go without other things like halogen bulbs. So ... was intending to use the rainwater system I am putting in as the source of the water but can't find anything in the water regs, on the WRAS site or anywhere else to say whether it is deemed acceptable to use Class B water in dishwashers. Anyone know?

It's not unusual for things to come out of a dishwasher wet so I reckon you should probably could only use rainwater if it was treated to meet drinking water standards?

Since your dishwasher contents are going to be rinsed in that water it had better be potable IMHO. I wouldn't want dilute bird poo in my glassware.

(BTW, dishwashers usually beat hand washing in studies, especially if they are run full and on the coolest setting viable for the load, unless the human dishwasher is very very careful. For me I am distressed by the amount of detergent and grot often not rinsed off manually-washed plates, and prefer the more thorough job that a decent dishwasher usually achieves. We usually use much less than 1kWh/day of our 4.5kWh/day electricity consumption for our dishwasher, less than the fridge/freezer for example.)

Rgds

Damon

Posted By: DamonHDFor me I am distressed by the amount of detergent and grot often not rinsed off manually-washed plates, and prefer the more thorough job that a decent dishwasher usually achieves

Why? is it the alleged link to Crones Disease or the visual aspect. Iam not a very 'green' or ecological person at all but I do use Ecover (used to use Tescos own but can't get it now) for washing up as it seems nicer to my hands.

Posted By: SteamyTea.......... Posted By: DamonHD For me I am distressed by the amount of detergent and grot often not rinsed off manually-washed plates, and prefer the more thorough job that a decent dishwasher usually achieves.

Why? is it the alleged link to Crones Disease or the visual aspect. Iam not a very 'green' or ecological person at all but I do use Ecover (used to use Tescos own but can't get it now) for washing up as it seems nicer to my hands.

I'm with Damon too on this one ST. Dishwashers are more hygenic. I'm amazed at the ammount of folks who do not rinse wash up liquid suds off crockery etc.. The thought turns my stomach. When you think about it washing up liquid contains degreasants, what's it doing to your insides. Re, running the dishwasher half full, buying a second set of crockery is possibly the cheapest solution, and then just rinsing between full cycles.

1) We have a slimline dishwasher.

2) Apart from not wishing to eat surfactants, detergents in particular have been fingered as endocrine mimics.

3) A dishwasher gets to higher temperatures than you can when handwashing. That alone is likely to remove more bugs and grease and kill more of whatever is left.

4) We have enough (cheap, second-hand!) crockery that we don't run out, forcing an early dishwasher run.

Rgds

Damon

James
I agree with you there, not got a clue what your Granny meant
Mine though was born in 1901 and lived to 103, she had no time for scraping the mould of food so just used to cook it longer. Not sure if that is good advice or not. Took a hospital 8 weeks to kill her off though C.Diff.

Posted By: pmusgroveThanks Damon - the problem comes when there are only 2 people in the home and the dishwaher keeps being run half full

I've seen an interesting double dishwasher that might be of interest. Each drawer (one top and bottom) is a seperate 1/2 size dishwasher. The idea is you take clean things out of one, use them, and put them in the other one. Whenever the dirty one is full you put it on and reverse the process. No need to empty the dishwasher either.

The problem comes when there are only 2 people in the home and the dishwaher keeps being run half full

I don't understand this - surely you own more than 2 plates? Just collect stuff until it's full, then run it.

You do have to rinse some crap off plates sat around for days otherwise dishwasher (at least on 'eco' setting) will miss bits.

Here's the german study into handwashing and dishwasher water usage rates. Turns out some people wash under a continuously running hot tap and thus use boggling amounts of hot water. Not hard to be more efficient than that!
ttp://www.landtechnik.uni-bonn.de/research/appliance-technology/publications/07-02-03-dishwashing

Our dishwasher runs off solar hot water which greatly reduces electricity consumption.

I agree with the comments by JSH, but I would qualify them by saying that any washing-up should use drinking water quality water (as IMO so should showering but perhaps untreated rain water is OK for a bath). The problem with rain water is not so much the rain water but the bird poo on the roof and the occasional dead mouse and alike unnoticed in the gutter, such things can easily contaminate rain water and make it unsafe without treatment. IMO rain water without treatment should have a 'for external use only' label and as such would exclude it use in the kitchen.
Peter

Most dishwashers, even on their "eco" setting, seem to heat everything up to temperatures and for time periods plenty long enough to kill bugs. It may not heat the water to high temperatures, but the drying cycle will normally heat the air and everything in the dishwasher to high temperatures. Most bugs won't tolerate being dried out during the drying cycle either, plus the surfactants and oxidising agents in dishwasher tablets are pretty aggressive biocides.

We can go a bit OTT about cleanliness, IMHO. The human race evolved pretty successfully by drinking untreated water for a couple of hundred thousand years. Water treatment was introduced to combat human-to-human pathogen transmission in the main, usually as a means of combating cross-contamination from waste water. There are very few animal-borne pathogens that are really harmful, and even those that are (like salmonella) need to be ingested in quite significant quantities to cause harm.

One thing that worries me is that there is a very strong body of evidence to show that our immune systems develop and are maintained by a process of challenge and response, something that we are threatening by our obsession with cleanliness. We develop immunity to common pathogens by being exposed to them regularly, challenging our immune system to maintain specific antibody levels at an adequate level. The process is similar to that used to provide enhanced immunity by vaccination and immunisation. The cleaner and more antiseptic we make our environment, the greater the risk that we will reduce our natural immunity to a wide range of pathogens. Additionally, the fast reproduction rate of pathogens means that they can quickly adapt and evolve defences against the biocides we now routinely use around our houses, risking the evolution of more toxic variants of common and relatively harmless pathogens that we've lived alongside for thousands of years. MRSA and ORSA are classic examples of this. They are, in effect, man-made pathogens, ones that evolved from a common bug developing resistance to man made agents and becoming significantly more virulent in the process.