Hoping there might be some irrigation experts hanging out in here who can help me with a couple of questions I can't find answers to re soaker hoses.
Firstly, background info: I've just installed a bunch of soaker hoses in my front garden – 5 in total, setup in parallel. There is a 2-way splitter on the faucet, one side of which connects directly to one soaker hose (15m long, with about 2m of garden hose in the middle to bridge a non-garden area), and the other side of which connects to about 15m of garden hose. Said garden hose then connects to a 4-way splitter, onto which connect four short (1-2m) lengths of additional garden hose which then in turn connect to four soaker hoses in lengths of ~7m, ~10m, 30m and ~25m. The soaker hoses are all the recycled rubber variety that slowly "sweat" water. Pope branded, from memory.
That aside, the questions:
1) This may be a dumb question, but I cannot for the life of me figure out the answer (either thinking it through or Googling) – or should I say, I think I know the answer but would like confirmation.
I know that I'm meant to use a 10psi pressure regulator to help the hoses release water evenly along their length, and to stop damage / blow-outs. Bunnings sell a 100kpa regulator, which I figure is close enough.
What I can't figure out is if I just need one pressure regulator for all five hoses (connected directly to the faucet, before the water splits into five separate paths), or five pressure regulators (one immediately before the start of each individual soaker hose – after the water splits into each separate path).
I think the answer is just one, as pressure and flow rate are different things, and hence the single regulator will keep the pressure around 100kpa no matter how many / how long soaker hoses I connect after it (until I reach the flow limit of the mains water / faucet anyway).
But, as I said earlier, I'm not 100% sure on this. Can anyone confirm?
2) On a similar note, I keep reading that you should only turn the tap on ¼ – ½ a turn when using soaker hoses. Does this rule still apply when you have pressure regulator(s) in place? I'm thinking it doesn't – that the ¼ – ½ turn rule is a primitive method of regulating pressure via reduced flow – and hence you can just turn the tap on full bore, but again, I'm 100% not sure. Anyone?
3) Do you actually need a backflow preventer with soaker hoses? I keep reading online that you should have one (for your health, and/or by law), but for some reason I'm struggling to find a shop which sells them.
Thanks in advance for any responses / advice – appreciate it!