Topic: collecting rainwater

[ACE]

How much over the average year would a 2.5 m2 shed roof collect. I was lucky to get a 1000lt water tank and thought it would help next year for a while to save hauling watering cans back and forwards to the tap as we are not allowed hosepipes on the site. Had a visit to pick a few veggies yesterday and was surprised to se it overflowing so I emptied a few bucket loads into a neighbours tub as she is not connected up her guttering yet. I cannot ever see me using a 1000 litres as I don't  believe in watering after the seedlings are established. I know this winter is wetter than normal, but what would you expect to harvest from your shed roof in a 'normal' year.

[squeezyjohn]

My shed roof is quite a lot bigger than that - and I've only got a 1000L IBC container but I'm fairly sure that this winter I could have filled it 100 times over!  Just in case of drought at the critical time it's definitely better to have more water than you need!  Especially if your allotment site is off the grid like mine is.

[InfraDig]

If the roof was flat ie rain fell on an area of 2.5m2, then 1m of rain (39.37") would make 2.5m3 of water ie 2500litres of water, assuming the rain fell vertically. If the roof was sloping then the rain would be falling on less than 2.5m2.

If the average rainfall is say 50" then there would be 25% more, and so on.

[Bill Door]

Well just to put a dampener on it You will also have to take into account evaporation and animal usage.  Also climate change.

Also my roof does not collect anything as I do not have one!!

My admiration for those attempting to calculate the rain collected.

Bill

[ancellsfarmer]

Well just to put a dampener on it You will also have to take into account evaporation and animal usage.  Also climate change.

Also my roof does not collect anything as I do not have one!!

My admiration for those attempting to calculate the rain collected.

Bill

Bill, you dont have to go without...,just get the 1000l pallet tank and cut the roof off it. Given that it is approx a metre cube, and that we may get 65 days of dry weather per year, you will need an average of 3.003mm per day to fill it. If you put a tap in it, how much will you drink?

[Bill Door]

Yes Ancellsfarmer I don't have to go without as I have a tap right next to my plots.  So even if I fall over carrying water I still water the plot.


Fortunately I don't drink the stuff.
Bill

[gray1720]

While we are on the subject of collecting rainwater, I have a query (I know, you can get cream for that).

How do diverters work when the butt gets full - is it just back pressure that stops them flowing?

I ask because if I set up a butt/butts (thinking a whole row) against the house, the location of the backhouse and the shed means that the downpipe is in the middle of the house, and the butts would block access to the back garden from the front. So I was considering a row on the other side with a diverter above head height so that I could run it across the access... then realised the problem!

Cheers,

Adrian

[InfraDig]

This gives some idea:

http://www.dailymotion.com/video/xkojm4_how-it-works-rain-barrel-diverter-kit-rainreserve_lifestyle

The output of the diverter has to be at the same level as the input to the barrel otherwise it will overflow or underflow, if it was higher or lower. The barrels can be chained together with simple pipe (all at the same level). Not sure if that answers your problem?!

[gray1720]

Hmm. That looks as though that idea is scuppered! Ho hum.

Still on the subject of collecting rainwater, any bright ideas about sourcing alternatives to ready-made butts? I am channelling my inner tightwad, and my love of improvisation, and was thinking in terms of those big blue barrels (especially for the back of the greenhouse, where I won't see it), but it seems that everyone selling them has had the same idea, and they aren't a lot cheaper than "real" water butts. Plus the only place selling within a reasonable distance of me will only deliver by the pallet of 4...

Adrian

[johhnyco15]

my plot here on the east coast has very sandy soil despite bags and bags of manure each year it still needs a lot of watering so i have 1 1000 litre tank and 5 250lt butts on my shed 1 250 lt butt on my small greenhouse and 1 250lt butt on my wheelbarrow shed and use this around the plot and if we have a dry spring im out of harvested rain water  by may the rest has to pumped by hand into cans and wheelbarrows it like its a knockout water going everywhere so harvest as much as you can  leave out buckets wheelbarrows even watering cans so they fill up over winter  as tesco say every little helps

[ancellsfarmer]

Probably wont be needing to water my back garden for the fore-seeable future! Came home on Thursday evening, after the frost reversal, to find it floating with water 4" deep. Outside tap supply apparently froze and released the olive,thawed, pipe free of tap, running at mains pressure, possibly for 5 hours. The water bill may bring tears! No deaths, damage or destruction . Oh dear!

[Vinlander]

Still on the subject of collecting rainwater, any bright ideas about sourcing alternatives to ready-made butts? I am channelling my inner tightwad, and my love of improvisation

Have you thought of putting pallets around a builders' bag and lining it with heavy polythene?

Cheers

[InfraDig]

Now that's a good thought!! On the tightwad side, and looking at my water bill, it costs me roughly £4 for a cubic metre of water (though that includes all sorts of other charges I can't avoid!), so that's approximately £1 for each 250litre filling. A 250L waterbutt costs £25 or thereabouts in Wilkos, so I need to fill it 25 times to break even, and that is without the stand! If you are on an allotment with no mains water then clearly you have very little choice, if you need to water. However, in a home garden, I think it needs a bit more thinking about roof size, rainfall, and how much water you think you want to apply over the season. Luckily I have "inherited" my two waterbutts. I am still on the lookout for cheap waterbutts though!! I did buy a submersible waterpump from Lidl (I think!) for about £30 to shift water about. I haven't done the calculations on its costs though!! More for amusement value!! (as are a lot of my Lidl/Aldi purchases)

[Vinlander]

I forgot to mention my allotment has a moderate slope and the shed is at the higher end - gathering too much rainwater for a dustbin or domestic cold water tank or any other 'gift of the skip'. I could dig a pond next to it and siphon the water direct to any plants more than halfway down the slope - but I'm happy with dipping cans - the place I chose to hide the (rather ugly) tank is also conveniently central.

I do use a small tank at the top of the hose to hold flash floods that couldn't make it through the hose in time. If I had room for a bigger tank next to the shed I'd have all the water 'on demand' and the hose would be empty most of the time so I wouldn't need to dump mulch on it every autumn to stop it freezing. Hmmm  - I could replace my upper compost heap...

The shed is tall enough to work on anything except an opposite slope - but obviously I'd need my little header tank on a 1.5m pedestal so all the 1.5m 'head' went straight into the hose.

It does take a little ingenuity to make a cover tight enough to keep mozzies out, but brown packing tape joining polythene sheet stays surprisingly rainproof for several months - I may put a goldfish in anyway, that much water never freezes through.

Cheers.