Rainwater Harvesting

darkpool

There seem to be a lot of articles here about generating your own electricity. But another way to save money and help the environment is rainwater harvesting. Rainwater harvesting is storing rain that falls on your roof and using it to flush the toilet etc.
It costs circa £3 for a cubic metre (1000 litres) for mains water. In the UK roughly between 1 and 2m of rain falls each year - that means a good few hundred pounds worth of rain falls on the average house. To flush a toilet takes about 10 litres. So that means each flush costs 3p.
Environmental benefits of rainwater harvesting include saving chemicals and energy to treat/ pump mains water. Perhaps the main environmental benefit of rainwater harvesting is that it means less water enters the sewerage network. During heavy rainfall water enters the sewerage network from roofs/ driveways. The sewerage network can't cope with this water and sewage overflows into rivers and streams through emergency overflows. This sewage kills most life in the river and the resultant toilet paper/ rags isn't nice to look at.
I'll admit rainwater harvesting isn't going to enable people to quit their jobs and retire to the Caribbean. But it will save some money and is good for the environment.

moonrakerz

Another poorly though out idea for saving money under the "green" banner. The cost of installing all the necessary equipment to "harvest" this water is considerable. It has to be collected, stored and filtered before it can be used.
Most households get a rebate on their water bills if they do not return roof rainwater to the sewers. This will, of course, be lost if you use rainwater to flush toilets.
AND......... modern toilets use 6 litres to flush not 10 (less for a partial flush) - it would be more cost efficient ( and greener) just to get a new loo installed !!

[Deleted User]

we have a rainwater harvesting system and it consists of a huge tank buried in the ground. Our rainwater is used to flush the toilet and fill the washing machine. Our system was put in when the house was built.

It would be a complete financial nonsense to do a retrofit and better to take the usual water-saving measures ie collect house water to flush toilets and use an ecocamel showerhead. We do this anyway ie shower water before it warms up is collected as is washing up water, so we only need to use rainwater for the toilets maybe 4 times a day so using 16 litres a day in our case. Every wash in the machine takes 50-52 litres so saving about 200 litres a week. Total saving for the week is 312 litres. It would take 4 weeks to save a cu m of water and a cost saving of around £3. You would be dead of old age before you would have clawed back the cost of a retrofit

Re energy usage well there is an energy cost as the pump has to work when ever water is drawn from the tank

darkpool

moonrakerz wrote: »

Another poorly though out idea for saving money under the "green" banner. The cost of installing all the necessary equipment to "harvest" this water is considerable. It has to be collected, stored and filtered before it can be used.
Most households get a rebate on their water bills if they do not return roof rainwater to the sewers. This will, of course, be lost if you use rainwater to flush toilets.
AND......... modern toilets use 6 litres to flush not 10 (less for a partial flush) - it would be more cost efficient ( and greener) just to get a new loo installed !!

Wow, I've never felt so much negative energy from one post. Someone have a bad day?

Yes I agree that rainwater harvesting might not be worth it if you live by yourself and are out working all day. However a lot of big companies do it. For instance Tesco do it in some of their stores. You think their architects are stupid?

Where rainwater harvesting works best is places where people congregate such as pubs/ schools/ offices etc.

Regarding the rebate from the water companies, well if I fitted a rainwater system to my house I doubt i'd phone up the water company asking to pay more money.

Below is a photograph that shows what happens when a sewerage system is overloaded. The material you see will be a mixture of toilet paper, sanitary rags etc. If rainwater harvesting helps stop this pollution I think it is a good thing.

moonrakerz

darkpool wrote: »

Wow, I've never felt so much negative energy from one post. Someone have a bad day?

Not at - all just being realistic !

darkpool wrote: »

Regarding the rebate from the water companies, well if I fitted a rainwater system to my house I doubt i'd phone up the water company asking to pay more money.

So you are going to put water (as sewage), which wouldn't have otherwise gone there, into the sewers (which YOU admit are overloaded)....and not pay for it either !

You are not only misguided, but you actually admit that you will be sponging off those who are paying their way - typical "green" zealot.......... !

Cardew

Apart from the obvious flaws in your posts, as pointed out above, you say you live in 'God's country(Glasgow)' - a statement in line with your earlier logic;)

My understanding was that in Scotland you don't pay directly for any water or sewerage - the charges are included in your Rates???

Perhaps you are just posting to help the English??

darkpool

ehhhhmmmm for a house with the roof drains NOT connected to the sewerage system the rainwater that you would flush down the toilet is replacing mains water. so the amount of water going into the sewerage system is the same.

while for most houses in the UK (with the roof connected to the sewerage system) rainwater harvesting reduces the water going into the sewers.

regarding not telling the water company, do you really think water companies want the hassle of people phoning up to amend their bill? rainwater harvesting is doing them a favour by reducing the need to upgrade drains

if rainwater harvesting is such a bad idea why do people do it? you think the likes of Tesco are green zealots?

thanks for your input cardew. it really is good of you to agree with everything that moonraker says. but perhaps it would make a more interesting thread if you had a little bit more original thought? You think people should only "help" people in their immediate area?

Cardew

darkpool wrote: »

thanks for your input cardew. it really is good of you to agree with everything that moonraker says. but perhaps it would make a more interesting thread if you had a little bit more original thought? You think people should only "help" people in their immediate area?

"wow - Someone have a bad day" you obviously don't appreciate TIC comments.

The reason why people 'harvest' rainwater is so that they don't pay for the delivered water, and hence don't pay for the sewerage on that rainwater - even though that harvested rainwater enters the sewerage system.

I am not sure of the exact figures but most rainwater on properties in UK does not enter the foul water drainage system. It either goes to soakaways to replenish the water table or to drainage systems.

I really fail to see how you deduce that harvesting water 'reduces the water going into the sewers'. If I harvest say 312 litres a week(like Kittie above) instead of having that water supplied from the mains, surely in both cases the 312 litres enters the sewer????

darkpool

Most rain that falls on roofs will enter the sewerage network. I'll admit modern thinking (past 15 years or so) is that rain falling on roofs enters the surface water system. But previously it was thought that rain falling on roofs should enter the sewerage system to flush it out. I'm sure we can all agree that most houses in the UK are over 15 years old - hence the roofs will be connected to the sewer system.

Regarding kitties example: say 1000 litres of rain falls on her roof and she uses 312 litres of MAINS water. That means 1312 litres goes into the sewer.

If 1000 litres falls on her roof then into a tank and she uses 312 litres that means 312 litres will go into the sewer. Depending on how full her tank is the remaining 688 litres might fill the tank or overflow into the sewer. ie a maximum of 1000 litres will enter the sewer.

So rainwater harvesting has a significant effect on water going into the sewers.

Jon_Tiffany

Darkpool is correct, the vast majority of houses discharge rainwater into the sewers. Its only on newer houses that the rain water is kept seperate.

darkpool

Southampton University Rainwater harvesting - 5 year pay back - i think that is good. What do the posters on this thread thing of that?

saving money and helping the environment - nice.