Water butt tap / pressure / flow rates

[kristen]

Sorry chaps, but my maths isn't up to it.

I have a water butt (52cm D x 94cm H which I make 200L) stood on bricks by my greenhouse .  It has a tap at the bottom which fits an irrigation pipe - I'm fairly sure its 13mm.

It takes ages to fill my 10L watering can, and blinking ages when the water butt is only half full.

I want to add some addition water butts (or maybe IBCs), probably up to a total of 2,000 L (greenhouse total floor area is 40' x 10', and I figure I could do with catching a 2" thunder storm when the tanks are not completely empty - I make that 1,887 Litres)

I am assuming I should join the tanks at the bottom, so they are self levelling.

What impact will it have on filling my watering can if:

1) I add more storage, but no more "head height"?

2) I jack up the size of the tap - 3/4"? or something silly like, say, 2"?

3) Or would I be better off getting a loo cistern that can trickle feed whilst I'm using the can, and the flush to quick-fill the can?

4) Or something else?

(I could stick a second can under the tap whilst I'm using the first, but I'd get distracted pollinating a melon plant I was watering, or somesuch ...)

5) I would like to fit drip irrigation instead of waiting to fill the can [I still need a fast tap because I will use the watering can on the plants in the nursery beds next to the GHouse].  Are there any pressure-related, or other, problems to take into account?

(I have read that the type of battery-operated automatic timer I use should have a valve that doesn't rely on pressure to shut off properly.)

Thanks for your help

[CeeBee]

It takes ages to fill my 10L watering can, and blinking ages when the water butt is only half full...

I am assuming I should join the tanks at the bottom, so they are self levelling.

I think some folk use a syphon tube at the top - has to be initially full, and of course reach to the bottom of the butts. Has the advantage of easy removeability, should this be needed, unlike connecting pipes at the bottom. But I've not even connected my own 3 butts at all...

What impact will it have on filling my watering can if:

1) I add more storage, but no more "head height"?

None, except that maybe the butts will be full more of the time.

2) I jack up the size of the tap - 3/4"? or something silly like, say, 2"?

I reckon this is the one, so long as tap and attached pipe (if any) are all large diameter. One of my 3 butts has a wider tap, and fills the can loads faster than the others.

3) Or would I be better off getting a loo cistern that can trickle feed whilst I'm using the can, and the flush to quick-fill the can?

If you can arrange it, then might be good. Cistern will have to be higher than watering can, and bottom of butts will have to be higher than cistern.

5) I would like to fit drip irrigation instead of waiting to fill the can [I still need a fast tap because I will use the watering can on the plants in the nursery beds next to the GHouse].  Are there any pressure-related, or other, problems to take into account?

(I have read that the type of battery-operated automatic timer I use should have a valve that doesn't rely on pressure to shut off properly.)

I've installed a drip watering thingy on my 6 hanging baskets this year, and I can plug more drippers into the main pipe for other things if it would be useful. It's for mains water though - includes a pressure regulator and a battery operated timer. Water butt water will be very low pressure, so make sure it's designed for this if that's what you intend to use. Perhaps there are systems with pumps? Don't Navitron do a PV well-pump? So far so good with my drip system. Just set on 2 mins once daily at the moment, during which time it dispenses about 5 litres of water. I expect I'll have to crank it up as the plants grow and if the 'summer' gets going, but still a great time-saver, and will keep the plants alive if I'm away.

[kristen]

All very helpful advice, thanks.  Syphon sounds less work, and more chance of success, for an unskilled plumber like me

I had realised that the loo cistern would need to be cascaded for height (although I think that bottom of cistern could match bottom of butts, once the water level falls to the last few inches not much of anything is going to help speedily fill anything, and I will have resorted to filling the butts via hose to regain some pressure!). I suppose any 10L intermediate tank with fast-ish delivery would do me - I could leave the can filling if it couldn't overflow. Does a "dispense-10L-then-stop" type of valve thingie exist?

I think putting energy into drip irrigation might be a better use of my time, I've got quite a few bits here so I could make a start.  Even if I turn it on manually whilst I'm checking the Toms for side shoots and doing the sex-thing with my Melons  that would be a start.

My irrigation plan:

Attach distribution pipe to the two-course brick foundation.

Insert one long, and one short, skinny pipe at 2' intervals. 

(I place my Toms along the path, and something else along the glass, all at 2' intervals.)

The Toms might be in there earlier in the year than the others, so I might need little taps on the shorter dripper pipes for the early part of the season. I'll cross that bridge when I come to it.

I was going to have a ring main all the way round - i.e. a T piece joining water butt to a loop around the greenhouse, and feeding it from both ends so-to-speak - thus making the longest run only 50% of the perimeter length, rather than 100% of it, to try to help the pressure.

A PV pump from some linked "storage" tanks to a single "delivery" tank is a good idea.  That way the delivery tank would always(ish) be full; overflow back to the Storage tanks; and give me a) good head height and b) more consistent pressure.  I reckon I use about 50L of watering cans a day for the G/House, plus anything up to another 50L on odds and sods I water nearby, so the pump has only got to be good for 100L per day!

I could get a particularly tall butt for the Delivery tank.

[Woodenstop]

Hi Kristen

What impact will it have on filling my watering can if:

2) I jack up the size of the tap - 3/4"? or something silly like, say, 2"?

If you get an IBC put a bigger spout at the bottom.

I made a spout out of 28mm copper pipe and it fills the watering can in about 3 seconds.



Andy

[kristen]

"fills the watering can in about 3 seconds"

Now we're talking!  I like the look of that, thanks.

[wookey]

We've got 5 180l butts cascaded using syphons - works fine. I'd prefer to bottom-connect as the technically more satisfying solution and it would stop mossies as lids could be screwed on, but SWMBO refuses to let me put holes near the _bottom_ of all the butts which does have obvious prolems in case of failure.

We speed filling by having a narrow hawes watering can(http://www.haws.co.uk/metal_cans_for_outdoors/4-5litre_long_reach_can.html) and just dipping it in the top of the butt. Fills in moments (until butt is 2/3s empty then its back to slow tap.). Very nice can - recommended.

A mate has 1/2"(?) full-bore valves and that works very well. Another has a loo cistern and that's even better (and much more fun :-) It could be automatically pumped if it was high relative to butts.

Oh, and if you drain the DHW tank into the water butts (don't want to waste water), then chuck the hose out of the door when done forgetting to remove the butt end, such that by morning all 5 butts have been completely emptied by the syphon you accidentally created, and there are a lot of young plants to be watered, then consider yourself _bl**dy lucky_ when it rains really hard that very night!

[kristen]

"We speed filling by having a narrow hawes watering can"

My can is too large for the opening at top of butt - it needs to come out at about 70 degrees, and is thus only about 1/3rd full.  I do own a nice hawes can too, but its way too small to water many Toms 

My parents had a circular corrugated tank by their greenhouse that must have been 1.5M diameter, you could dunk anything in that ...

My butt has a hose-sized connector at the top.  I reckon I can stick a 1/2" hose though that for the syphon, and thus still have a lid.

Should I get black IBCs, or would painting clear ones be good enough? (Then I could leave a small vertical strip unpainted for a level indicator, I suppose)

"consider yourself _bl**dy lucky_ when it rains really hard that very night!"

The "report to moderator" link is dangerously close to that sentence! I'm sure this forum has AI and knows which "moderator" to report to!

[Much]

We've got 5 180l butts cascaded using syphons - works fine. I'd prefer to bottom-connect as the technically more satisfying solution and it would stop mossies as lids could be screwed on, but SWMBO refuses to let me put holes near the _bottom_ of all the butts which does have obvious prolems in case of failure.

No reason not to combine the best of both worlds! a syphon can automatically restart once the water in the source tank gets over the highest point (plus the level of water in the supplied tank - I assumed empty):

[Ivan]

Wouldn't there be a trapped air bubble that would prevent the syphon restarting? I'd have thought you might need a manual air bleed on the syphon in your diagram to remove the air if the syphon has been lost.

[kristen]

Isn't this the extra height of water in the "inlet" tank going to push the air bubble back out?

[Ivan]

I'm only guessing but unless the pipe is small diameter, you'll end up with a slug of air at the top which won't move. The height of water in barrel1 will push air through until the water reaches the top of the syphon, at this point, it will compress the slug of air sufficiently for a small amount of water to bypass it at the bottom, but flow rate would be low - I suppose it depends on how fast it's intended to syphon across, as to whether or not this is a problem

[kristen]

"it will compress the slug of air sufficiently for a small amount of water to bypass it at the bottom"

Ah ... hadn't thought of that.

[Ivan]

All you'd need to sort that would be a manual air bleed T'd into the top of the syphon. Or if you did your sums, you might find that a T going to a blanked of piece of pipe of sufficient length would accept all of the air from the top of the syphon as it compresses under head of water, thus eliminating the need for a air bleed. That sounds almost patentable.

[solar_cambridge]

The bad thing with that setup is that you are sucking all the sediment from the bottom of the first tank and dumping it in the second.  With rainwater tanks you don't want to disturb the sediment except to remove it.

A better solution would be this (I don't have a drawing package handy, but will describe as best I can!) You have two connections near the bottom of both tanks. Inside the first tank you connect a length of flexible hose (shorter than width of tank) to the exit of that tank. On the open hose end you attach a float that is tethered to the hose by a short length of rope. The hose is weighted so that the open end is always below the surface of the water.

This solution means you are always filling the second tank with neither the sediment from the bottom or the scum that is floating on the surface. It also doesn't rely on any syphon effect. Once the hose drops to the level of its outlet, the water stops and you never draw off the sediment.

Now, if you want to automagically remove the sediment from the first tank you can use a syphon which is almost touching the bottom of the first tank and has a shorter length outside the tank. Then when you get a lot of rain, the syphon kicks in and the sediment is 'sucked' up the syphon and dumped outside the tank.  Remember to use a short length from the syphon outside the tank, otherwise you'll empty the lot 

Martyn