new garden hose needed

**DannyK** · 31-03-2015, 08:01 AM

I have a 150' garden and find the flow from a 12mm (1/2") hose more than adequate.

Most the fittings that go on taps are for 12mm hoses. The 15mm figure refers to the outer diameter of the copper pipe. The id is 12mm (1/2").

I rigged up a bib tap 3/4 way down using 20mm MDPE piping which I ran at the base of a fence and is barely covered with soil. MDPE is far more durable than hose and 50m will cost �32 from Screwfix. Any surplus MDPE can be adapted to make cloches.

I fitted a 15mm isolating valve towards the end of my hose using 15mm copper and jubilee clips. Saves a walk back to the tap, especially when the sprinkler is out of sight.

**Sarico** · 31-03-2015, 09:24 AM

I have a 100 ft of extendable hose and is not that a problem when you take it away. You could put a tap at the end of garden using mdpe pipe. Better if you burying them to avoid that when winter comes doesn't freeze

**Kristen** · 31-03-2015, 10:08 AM

It probably depends a bit what your water pressure / flow is to start with.

My hose originally came off a 1/2" extension to the kitchen sink supply. Flow was dreadful, so I fitted an outside tap direct off the mains instead. Much better!

However, I then found that using a "reasonable" length of 1/2" hose fairly dramatically reduced the flow ... so now we only use 3/4" hose around the garden. Downside is that it is a lot heavier to lug about.

I have buried MDPE pipe all the way down the garden, with taps at intervals (such that 50M of hose will reach any part of the garden from a tap and 25M will reach most of the garden). Because of the dramatic difference between 1/2" and 3/4" hose I took the decision to install 32mm MDPE pipe so as not to further reduce flow due to friction.

Comparing the flow at the tap with that at the end of 100M length of hose/pipe:

1/2" hose takes 85% longer to fill a bucket
3/4" hose is 20% slower
32mm MDPE is 10% slower

Here's the test I made based on the time it took to fill two buckets:

Direct from outside Tap 1m12.5s

50M x 1/2" hose 1m52.1s +55%
100M x 1/2" hose 2m14.1s +85%

100M x 3/4" hose 1m26.8s +20%
200M x 3/4" hose 1m35.2s +31%

32mm first tap 1m20.1 (nearest to supply)
Tap 2 - 100M x 32mm 1m28.1s +10%

**Sarico** · 31-03-2015, 05:13 PM

Well if I'm telling you how long take me to fill a bucket you will get crazy. You only talk about seconds more to fill a bucket but you will save time going back and forward to fill bucket. Plus when I water my plants with the hose I only have the tap half open so doesn't damage the pla t with high pressure water coming out the hose gun.

**Potstubsdustbins** · 31-03-2015, 08:16 PM

First if you use a fixed system i.e. not a hose pipe and want to comply with the regulations. That pipe must be buried to a depth of at least 450mm. The trench, pipework, double check valves and isolation valve will have to be inspected by your local water company before you back fill. Suitable pipe would be MDPE or soft rolled copper (mega expensive).

Should you not comply and they find out they have the legal right to disconnect your water supply. This action is a last resort if you do not comply with their requests but I have known it to happen several times over the years.

Before you go enlarging pipe work the thing to do is first check what size of pipe is you incoming main and then make sure the stop cock is fully open. Fully open the cock and then close it half a turn, this will help stop it jamming and make it easier to turn off in the event of an emergency. It will do no good what so ever putting in larger pipe down stream of the main stop cock than the pipe upstream of it.

**seneca196** · 31-03-2015, 08:36 PM

If I have a 12/15mm pipe outside (coming off a utility room extension) and then join a 20mm piece of mdpe pipe (25m long) and then put a tap on the end, I will have a new extension tap at the other end of my garden. Will going from 12mm tap, to 20mm mdpe, then back to 12mm hose mean any serious change in pressure? This sounds like what DannyK has (first reply)
I can then attach a 25m length of hose to the new extension tap to go all over the far end of my garden and even half way back towards the house if needed. Also, now that I would have the new tap I could also use it for filling watering cans, a sprinker and in future, an irrigation system for my container trees.

May sound a bit convulted and fussy, but I only intend on doing it once, so want to get it right...well as right as possible! And for that very reason I'm looking at one of these -
Tricoflex Performance Hose Pipe 12.5mm x 25m - Tricoflex Hose Pipes - Garden Hose Pipes - Hoses And Watering

**seneca196** · 31-03-2015, 08:46 PM

Just seen your response before posting (potstubsanddustbins) so am a bit taken aback. I always intended to run my 20mm mdpe, only slightly buried like DannyK's, from my 12mm outside extension tap. I would always use that as the "master tap" and always switch on and off from that first. I know that would mean having to turn two taps, but that seems like a small inconvenience compared to the piece of mind from knowing the house and garden water supply are always separate.

Always wanting to honestly obey all rules and regulatons (ahem!) I can see why a lot of people I've asked have told me to just run a 50m length of 12mm hose straight from my tap and hide it near the bottom of a fence.

**Potstubsdustbins** · 31-03-2015, 09:04 PM

I did say if you want to obey the regulations.

The problem we face nowadays is the regulations are there for just about everything we do from an outside tap to an outside light, but lay people tend not to know them, then end up scratching their heads when the authorities come a knocking.

One of most important parts is the fitting of a double check valve, This is the bit of kit that prevents contamination of the potable water supply. If that happens they will find out and come looking, just as they now have check markers in most brooks, streams and rivers.

**Kristen** · 01-04-2015, 10:09 AM

Originally posted by Sarico View Post

You only talk about seconds more to fill a bucket

Not exactly - its 80% longer, than means using a 1/2" hose would take me nearly twice as long to water the plants as using a 3/4" hose. I only used filling-a-bucket as a means of measuring the flow of water from the hose / pipe, not as an actual means of watering the plants.

Originally posted by Potstubsdustbins View Post

It will do no good what so ever putting in larger pipe down stream of the main stop cock than the pipe upstream of it.

I disagree with that as surely there will also be friction losses in the pipe? So connecting a same-bore pipe as the extension may have greater friction losses than extending with a larger-bore pipe such that there is a significant difference in outcome. I doubt it is going to matter for 25-50M but beyond that I think it is worth installing a larger diameter "main" pipe.

Originally posted by seneca196 View Post

I always intended to run my 20mm mdpe, only slightly buried like DannyK's, from my 12mm outside extension tap. I would always use that as the "master tap" and always switch on and off from that first. I know that would mean having to turn two taps, but that seems like a small inconvenience compared to the piece of mind from knowing the house and garden water supply are always separate.

When I installed mine, originally, it wasn't connected directly to the mains (as that is right around the far side of the house, that connection only happened when I had the drive dug up for other reasons!)

So initially I connected a hose from my outdoor tap to the first tap on my "extension pipe", and then used the taps along the extension pipe. Sounds like that would conform to the Rules as the double-check valve etc. is provided by the initial outdoor tap.

**Potstubsdustbins** · 01-04-2015, 01:18 PM

I have only been a register plumber for 42 years and a master plumber for 38 ..... nice to know I don't know what I am talking about.

A stop cock will only allow a certain amount of water through the face aperture the amount will depend on the pressure behind the water supply. You could fit a larger stop cock to increase the diameter of the face aperture but even this would have little effect as upstream of that is the boundary box again with a stop cock, this one belongs to the water company and so is none adjustable.

**Kristen** · 01-04-2015, 01:39 PM

I'm no expert, but if the stopcock allows, say, 2 gallons per minute through and you then put that "flow" through a long 1/2" pipe are there no friction losses that reduce the flow that you then get out of the far end of the pipe?

For example, I have perhaps 200M of 32mm pipe down my garden. The flow rate (which I measured as the time to fill a bucket) at the first tap on that extension pipe (nearest the supply) is faster than the tap at the far end.

As per my earlier post:

32mm first tap 1m20.1 (nearest to supply)
Tap 2 - 100M x 32mm 1m28.1s +10%

so the tap which is 100M down the pipe took 10% longer to fill a bucket.

I might be using wrong terminology, but if I am standing there wanting to give each plant, say, one litre then I want that to be the shortest time possible (without blasting the plant out of the ground!) so that it takes me as little time as possible to water the garden and from my experiments a longer length of pipe reduces the flow rate.

**Potstubsdustbins** · 01-04-2015, 01:59 PM

Pressure drop along a pipe is a decidedly tricky thing to calculate. There is certainly a pressure drop therefore a reduction in flow rate along any pipe but there is only a certain amount of water that can pass through the upstream orifices no mater what the pipe size down stream. The main effect of a larger bore pipe in these circumstances is to form a kind of reservoir. To do your experiment correctly you should first let the tap run unrestricted for several minutes and then do your measuring preferably using a calibrated weir cup.

The other thing to bear in mind is that Ofwat only expects water companies to deliver 9trs approx. 2 gallons a minute. Many do more than that especially in the urban areas or if you are close to the reservoir out in the country but if you are a long way off the ring main or at the end of a long leg that's the least they can get away with.

**Kristen** · 01-04-2015, 03:02 PM

Good point about the pressure drop for the "reservoir", thanks. If I turn the stopcock (to my garden pipe) off I can still comfortably fill a 2 gallon watering can before it runs out of reserve pressure!

When I have a moment I'll redo my "time to fill a bucket test" with the tap running freely before putting the bucket under it. Almost certainly my original timing was from "turn tap on" until "bucket full" which might well have had some excess force for the reservoir effect which may have influenced my figures.

**arpoet** · 01-04-2015, 03:28 PM

This all seems a bit complicated to me. I would just get a hoselock connector for the tap and say 3 standard hosepipes all fitted with hoselock connecting joints. This give you pots of flexible combinations to move water to where you need it.

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