Surely new houses should be using rainwater for flushing toilets etc and not fresh water? Why isn’t this done more? Is it the cost of double pipe work and water storage containers and pumps?
There are a few reasions: The water regulations used to be prohibitively complex. They've got better but old habits die hard in construction. Rainwater isn't very clean by the time it gets to the tanks (i.e. after it's washed your roof and gutters) so storing it for any length of time is tricky - results in black sludge in the tank. You can chose to do that yourself, but a system that is provided for you has to comply with more H&S rules in case you don't understand it and try to drink it and also to make sure you can't cross contaminate the mains system by connecting your manky rainwater into it. So yes, the requirements for labelling and separation are quite onerous and the costs of filters is a bit steep. Rainwater storage for use in the house is not SUDS. SUDS storage has to be normally empty of water for it to work. SUDS is often a planning requirement. So you have to put in one big tank/store to meet planning. If you want to also use rainwater for toilet flushing then you have to have another big tank. In most cases, one tank is as much as they can sensibly find room for without major excavation.
Gardening on the edge of Exmoor, in Devon
“It's still magic even if you know how it's done.”
All of what @raisingirl said and more. The cost of a rainwater harvesting system can run to around £5000 once you've excavated for the tank and fitted the additional plumbing and filters. Welsh Water currently charge around £1.29 for 1000 litres of water so it would take one person about 80 years to use enough water to pay that off, and that's only if they used rainwater for everything and you don't take into account running costs.
A conscientious person should be using less than 125 litres of water a day on average so the water level in the tank wouldn't drop fast enough to leave capacity to manage storms. As raisingirl says you'd need a second tank or similar to deal with the overflow and you're duplicating costs by doing that.
Rainwater harvesting also sends the water to the sewage system rather than to a watercourse, although this should be happening with tap water anyway. The irony of the new rules is that once you've harvested rain water it gets classed as tap water so you can legitimately open the tap to your harvesting tanks and send the whole lot to the foul drains whereas it would be illegal to pipe rain water directly from your downpipes into the foul drains.
If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
I've seen some great driveway designs using 2 strips of hard surface to park the car on and planting or ponds around it. Maybe a green roof on the car port. I doubt it's practical for most houses and families though sadly.
Ah right, thanks Rainsin and WE. I knew using rainwater wasn’t suds but couldn’t see why they were moving towards a half solution. It does look complicated and expensive.
It's fairly straightforward to DIY it, if you're any good at plumbing. You need to be able to undo it reasonably easily when you decide to sell your house. It's less easy to provide it as a commercial construction 'offer' that has to comply with all the regulations. What you do in your own house is largely your own affair as long as you don't risk contaminating the mains water supplies or flooding your local sewers.
Gardening on the edge of Exmoor, in Devon
“It's still magic even if you know how it's done.”
I don't see why rainwater for a toilet would have to be expensive, it doesn't have to be buried and if it were not it would not need a pump. A small ish tank (weight dependent on structural concerns) above the toilet but below the gutters would work, gravity fed both ways, If the tank was emptied from the bottom sediment could not build up, and you can put a flushing system on your rain collection to avoid most of it anyway. Of course if you really want to try flushing a toilet with rain water all you need is a bucket, pour it down the bowl when you are done. Here every little town has it's own water well and pump so water going off is fairly common!
I entirely agree with you Skandi, in principle. But: In some parts of the UK, 6 to 8 weeks with no appreciable rainfall is fairly normal. A tank large enough to store all the water needed to flush a toilet for that period of time would be too big to go inside the house (or on the roof). Therefore you'd need to have a back up arrangement which allowed you to swap to mains water when the rainwater tank was empty. That means having a non potable source (the rainwater) connected to a system which is also connected to the potable source (the mains) and there would then, in the minds of our Water Companies, be a risk of cross contamination by back siphoning. Therefore the rainwater system would have to comply with some regulations, which makes it more expensive
Gardening on the edge of Exmoor, in Devon
“It's still magic even if you know how it's done.”
Ah right, thanks Rainsin and WE. I knew using rainwater wasn’t suds but couldn’t see why they were moving towards a half solution. It does look complicated and expensive.
The new Welsh SUDs regs will prioritise collection for use above all other methods of dealing with rain water. Sadly the cost will probably be enough to let most developers get out of doing it. Most housing associations now provide water butts as standard on new housing so this will most likely end up being common practise on all housing now too.
If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
The GW magazine just got shoved through the door and I see that Monty is discussing better water use in gardens so I thought I'd bump this thread back up. A really interesting article and the info about Cape Town running out of water is quite eye opening. I notice though that the magazine also features a big review article on hoses complete with smiling model happily spraying water all over the leaves of plants rather than down at the ground. I'm sure it's harvested rainwater though right GW?
It hasn't rained much here in a month now and I've still got about half my stored rainwater available. I don't think we're far off having a hosepipe ban this year now though.
If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
Posts
The water regulations used to be prohibitively complex. They've got better but old habits die hard in construction.
Rainwater isn't very clean by the time it gets to the tanks (i.e. after it's washed your roof and gutters) so storing it for any length of time is tricky - results in black sludge in the tank. You can chose to do that yourself, but a system that is provided for you has to comply with more H&S rules in case you don't understand it and try to drink it and also to make sure you can't cross contaminate the mains system by connecting your manky rainwater into it. So yes, the requirements for labelling and separation are quite onerous and the costs of filters is a bit steep.
Rainwater storage for use in the house is not SUDS. SUDS storage has to be normally empty of water for it to work. SUDS is often a planning requirement. So you have to put in one big tank/store to meet planning. If you want to also use rainwater for toilet flushing then you have to have another big tank. In most cases, one tank is as much as they can sensibly find room for without major excavation.
“It's still magic even if you know how it's done.”
“It's still magic even if you know how it's done.”
In some parts of the UK, 6 to 8 weeks with no appreciable rainfall is fairly normal.
A tank large enough to store all the water needed to flush a toilet for that period of time would be too big to go inside the house (or on the roof).
Therefore you'd need to have a back up arrangement which allowed you to swap to mains water when the rainwater tank was empty.
That means having a non potable source (the rainwater) connected to a system which is also connected to the potable source (the mains) and there would then, in the minds of our Water Companies, be a risk of cross contamination by back siphoning. Therefore the rainwater system would have to comply with some regulations, which makes it more expensive
“It's still magic even if you know how it's done.”