I have just installed a dripper (bushes) and leaky pipe (veg. patch) system. Both are fed from a butt at the highest point in the garden and I have either bushes OR veg. running (But not both together)

It works well enough but I feel I could use a bit more pressure so if I connect another butt (At the same height) will that increase the pressure i.e. Is the pressure only a factor of height, or will an increase in volume help.
Also, if I connect both the bushes & veg together will that halve the pressure.??

BTW I want to avoid using pumps at this stage.

Hi Loso,
The pressure will be the same but the volume may improve. I say may because it is then depending if the pipe is running to maximum for low pressure this I doubt so you may get more water through the pipe which surely is what you are after.
The pressure is determined by the height that you have the barrel above the outlet.
JB.

the pressure is directly proportional to the height difference between the outlet and the surface of the water in the butt, more butts presumably will mean they stay fuller longer which means the pressure wont drop as quickly as water is used from the butts ie drawing 40 galls from one butt will mean zero pressure at the end, but drawing 40 galls from 4 full inter connected butts means they are still 3/4 full and have about 3/4 the pressure you had at the start. flow rate through the pipe is related to pressure, size of the pipe and (on small bore pipes particularly) friction between the walls of the pipe and the water.

Thanks guys, that pretty much amswers all my queries and yes Johnboy more water flow is what I want, but being me I just didn't articulate it correctly

Ultimately I think I might go for three butts, but intend to add one now and see how that performs.

What you have to ask yourself is "does my butt look big enough for this?"
Kev

Hi Loso,
The district pressure in any town system is dependent and the height of the water tower or height of the reservoir outlet unless a water ram is used.
Is there any possibility of raising the height of the barrels that you are using.
My tap pressure is so high that I have to reduce the flow. I an fed from am aquifer from the Elan valley in Wales to Birmingham and the outlet of the reservoir is 310FT above the point my tapping is taken.
My irrigation system is double fed and by this I mean that I feed both ends of the irrigation pipe and this makes the distribution of water very even along the row. So often you see irrigation where the flow decreases as it goes down the row. Now I am using my pressure from the main to do this but it would work equally well on a lower pressure system so I am wondering if this may assist you. If you install a second barrel and run a pipe to the other end of your existing system. This could well increase you volume and resolve your problem.
JB.

Johnboy,
Thanks, that's quite a brilliant idea (Running a pipe from second butt to end of line) wish I had thought of that. It maybe tricky on the bushes 'cos of where the pipe end is, but on the veg. easy peasy

While this is still a hot thread can I ask about float switches in the water butt. (I am pumping up a hill to fill them) I'd like to automate the filling by which I mean switch the pump on and off as required. I came across Stuart Turner Ltd. who seem to have a nice looking float switch to do this.

Do you guys know any other people who do 'float switches' (I always try to look around and not just take the first thing I find)

try maplin.co.uk they may well have something.
the other way is to use a ballvalve at the tank end to shut off the pipe and an inline pressure switch at the pump end to kill the pump before the pipe bursts. just like a domestic power shower pump !!

Thanks Alan, due to OH being hospitalised I only just got around to ordering the float switches. Yes, I went to Maplin since the other people didn't answer my e-mail

I finally got my irrigation sorted out and it hasn't stopped raining since!