Water Butt - mains topup?

[ukwill]

I've bought a lawn popup sprinkler system and am thinking about putting in a large water butt to be the primary water source. Obviously during dry periods, when the butt is empty I'd like to feed it from the mains water supply.

Has anyone done this? Is it relatively straightforward? (I'm trying to do my bit for the environment, rather than simply taking it direct from the outside tap).

I appreciate that I may need to add a pump as the pressure/flow might be inadequate for the system.

[tomsugden]

I have two water butts joined together, and a pump connected to a smart plug that allows me to schedule watering the garden. I manually fill it with a hose in dry spells when it's empty, but it only needs doing a handful of times over summer.

[Ambleton]

Sure it wouldn't bee too difficult to rig something up.

If you put a cistern fill valve at about 10% up the water butt then you will get a fresh water supply up to that point. Then the remaining 90% will be rain water.

[Martin30]

Do you have a little room to store a 1,000 litre IBC? £125 or so to get a clean, used one delivered and holds 1,000 litres unsurprisingly.

I find ours fills up about 300 litres every time we have a decent few hours rain, and I would imagine you would use 150 litres max on a sprinkler system. That builds you a decent buffer.

Martin.

[biggiles]

Pretty easy. Hozelock (and others) sell a "butt pump" (!) which is designed for exactly this purpose.

Probably easier to just top up with a hosepipe when it's low, as otherwise you run into all sorts of regulations about air gaps from the valve, to make sure there is zero chance of your roof water going back into the mains.

[ukwill]

biggiles said:

Pretty easy. Hozelock (and others) sell a "butt pump" (!) which is designed for exactly this purpose.

Probably easier to just top up with a hosepipe when it's low, as otherwise you run into all sorts of regulations about air gaps from the valve, to make sure there is zero chance of your roof water going back into the mains.

Thanks for the feedback chaps.

I didn't know IBC's were a thing so that's a great start! They look exactly what I'm after, as it will be tucked away out of sight.

I have 8 popups, each specced at 4 litres/min (at 2bar). So roughly 30-35 lit/min total required. What do people do about hosepipes? From what I can make out one hosepipe can handle around 12-17 lit/min. So are you supposed to run more than one line?

[Meprobamate chic]

One hose will be fine if you add a pump - and to feed it from a water butt or IBC you will need a pump, or it won't work.
And at that sort of volume of water you won't get many green points from a water butt type system - even with an IBC you will drain it in half an hour and end up using mains water.

[paulrockliffe]

I've looked at this a few times, but I couldn't make it make sense. Can you store enough water to get you through a dry-spell? Possibly if you use it to run a soaker hose through your beds, but not if you want to water your lawn.

I did the maths on mine, about 150sqm metres, so an inch of water is the best part of 4 IBCs. To get good water into the soil you're doing that once a week minimum in the summer, so frankly a water butt is going to go nowhere and you're only going to use it when it's not refilling, so you'll end up doing 95% off the tap.

If you want to run multiple sprinklers at the same time off a pumped supply, so you can program it to run without messing with valves and have space for an IBC they can make some sense - It's fairly simple to wire it so it pumps until it's empty, then starts again when it's full, especially with an Arduino. Probably simple to work out a weekly duration based on temperature and rainfall and leave it to run on it's own.

[biggiles]

ukwill said:

biggiles said:

Pretty easy. Hozelock (and others) sell a "butt pump" (!) which is designed for exactly this purpose.

Probably easier to just top up with a hosepipe when it's low, as otherwise you run into all sorts of regulations about air gaps from the valve, to make sure there is zero chance of your roof water going back into the mains.

Thanks for the feedback chaps.

I didn't know IBC's were a thing so that's a great start! They look exactly what I'm after, as it will be tucked away out of sight.

I have 8 popups, each specced at 4 litres/min (at 2bar). So roughly 30-35 lit/min total required. What do people do about hosepipes? From what I can make out one hosepipe can handle around 12-17 lit/min. So are you supposed to run more than one line?

You don't run them all at the same time. I have an irrigation set up with 4 switched valves, as the 2hp pump won't power all of the pop-ups at the same time. (They are about 800-2000 litres/hr, running on 25mm MDPE pipes). Hunter (and others) do timers which switch each valve on/off. But you're looking at £50-100 for the controller, £20 for each valve... it adds up quickly, so isn't worth it for most people. If running off normal hosepipes, a manual option is the 4-way tap heads by Hozelock and others.

IBCs are very efficient ways to store water, and you can connect an unlimited number together to give you more storage capacity.

[Andy RV]

Biggiles, do you have any information on the pump which your using?

[hunton69]

Previous owner installed a 2,000 litre tank doesn’t last long during a dry spell so jumped at this when it came along

[ukwill]

Wow! I thought this would be a relatively simple task, but it appears anything but.

I assume sprinkler systems have to use water storage systems of some sort (and a pump). I figure 20min watering x3 weekly. So for my install that’s 640 litres for 20mins. So 2 IBCs should cover it? Then mains water top up.

Is that roughly it or am I missing something?

[paulrockliffe]

ukwill said:

Wow! I thought this would be a relatively simple task, but it appears anything but.

I assume sprinkler systems have to use water storage systems of some sort (and a pump). I figure 20min watering x3 weekly. So for my install that’s 640 litres for 20mins. So 2 IBCs should cover it? Then mains water top up.

Is that roughly it or am I missing something?

My tap runs about 15l a min and is more than enough to run one of the sort of sprinklers you're talking about, but not two. You generally don't need pumped storage as you just run one at a time.

But getting good even coverage you pretty much always need a few sprinklers in different locations, so you're either then manually swapping hose around, or opening and closing valves or paying a lot of money for powered valves - though you can do this bit cheap if you're handy as every broken dishwasher or washing machine has a water inlet valve that is perfect for this.

You're better off watering once a week for longer than every other day as you want to convince the grass to grow it's roots deep, they won't do that if they don't need to.

How big is your garden? https://www.lawnsmith.co.uk/lawn-care-advice/lawn-... reckons an inch a week, so a cubic metre is good for 40 square metres. But as I said, it likely doesn't really matter how many IBCs you have as you'll be rainfall-limited at the times of year you want to water the grass.

My view is the reason to store and pump is simply so you can run all your sprinklers together, without messing with valves, the water saving will end up negligible. You're at about an hour to refill an IBC, so you can run 8-10 cubic metres with the system on/off all day. Although if you store more you can get more on before you start refilling, you'll still be flow-limited when refilling, so you might not gain much from more IBCs.

If you decide to pump it, you should make it your challenge to get the water on the lawn as quickly as you can - fit loads of heads and a few pumps and it'll be spectacular while it's going off!

[ukwill]

hunton69 said:

Previous owner installed a 2,000 litre tank doesn’t last long during a dry spell so jumped at this when it came along

I believe I’m after an IBC, not an ICBM.

[LooneyTunes]

ukwill said:

I have 8 popups, each specced at 4 litres/min (at 2bar). So roughly 30-35 lit/min total required. What do people do about hosepipes? From what I can make out one hosepipe can handle around 12-17 lit/min. So are you supposed to run more than one line?

Don’t skimp on pipe diameter, especially if you have long pipe runs. Friction will murder your flow rates.

We mainly use 3/4” and 1” tricoflex for hosepipes around the garden all held together with geka connections (gender neutral, don’t restrict flow, and make it easy to join different bores of pipe together) along with a couple of beak <-> hozelock adapters I made up for connecting regular garden centre accessories. The connectors are cheap (not much more than hozelock) but make sure you’re sitting down when you look up the price of the hoses! Underground stuff is 20/25mm mdpe.

If you’re topping up a water butt from the mains, you could do it automatically with a float valve system or have the mains feed directly into your pipe work but if you do have mains and rainwater together don’t forget non-return valves (you want a one way flow from mains to tank!).

[paul.deitch]

Depending on your water table don't discount a well. That's what I did. We have very sandy soil and a high water table. It cost 250 to go down 8 meters with I think a 2 inch pipe with a filter on the end.

[MXRod]

We have an IBC collecting from the house roof , that is fed from a downpipe interceptor and a buffer barrel (to settle out moss and dust ).Even a short period of rain will fill the IBC to overflowing , just a pity we do not have room for a second one
Also 5 ex fruit pulp barrels , about 250lt each collecting from shed and greenhouse .The barrels are linked together at the bottom to equalise the levels and have a take off tap for watering can use as well as linking to the pump if req , the pump is also used to transfer water from the IBC at the front of the house to the barrels at the back .
A mains fed 4 zone micro irrigation system feeds hanging baskets and greenhouse benches , it waters for about 2 mins per zone 3 times a day
For bulk watering of lawns and flower beds we use the irrigation pump and larger diameter hose bought in France ( they are big on storing and using rain water for irrigation ) this pumps from the stored water ,also using professional sprayers , and we have yet to run out of stored water.

[biggiles]

Andy RV said:

Biggiles, do you have any information on the pump which your using?

It's a borehole pump Andy RV, so won't really work with IBCs/water butts. It's a Grundfos SP3 type, three-phase, 2.2kw (more than I thought - around 3hp).

My point was that a typical little water-butt pump won't manage many sprinklers, so you need to set it up to do one at a time, either automatically or manually.

[GranpaB]

Water butts are great but what fills it up in the summer, when you need and use it and little rain?

[ukwill]

So my little list so far is:

1 or 2x IBCs

https://www.kingfisherdirect.co.uk/1000-litre-reco...

And either this
https://www.gardena.com/uk/products/watering/water...
with this
https://www.gardena.com/uk/products/watering/water...


or if not gardena, then this
https://www.amazon.co.uk/Claber-90829-Hydro-4-Seal...


A suitable pump (for 8 sprinklers and either a drip line or micro sprinklers for a border run)

and the pipework/hoses and associated gubbins to get the mains top up in place.