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We're in the middle of a drought with 'day zero' estimated around May next year so I've decided to go off grid, or partially off grid in an effort to ensure I still have water at home.

I decided to use my borehole water for most of the house and just use council water for human consumption such as drinking and cooking. This has meant I've had to split the plumbing into two circuits, borehole water now supplies the 5 bathrooms and council water supplies just the cold water on the kitchen sink, the coffee machine and the soda machine which are both permanently plumbed in. There's also an option to revert back to council water for the entire house as well.

It's meant some serious DIY plumbing, although probably not plumbing as you know it, over the last month or two.
 
any pics marvo ?

and did you get the bore hole tested before hand?
 
Before I start with questions I thought I'd try buttering you up with a few photos first.

p4.jpg
New pipework for the coffee machine.


P3.jpg
Alterations to the water main coming into the house.


p2.jpg
Installing pipework from the bore hole to the house.


P1.jpg
Changeover manifold.

Black class 10 HDPE pipe is bore hole water in.
The 15mm copper coming out of the ground is council water to supply sink, coffee m/c and soda machine.
The 22mm copper going into the ground is borehole water to the rest of the house.
The open 110mm drain pipe has a hand valve to close off the council water to the rest of the house.

As show the system is all still running on council water only because I've not finished installing the filters and stainless steel pressure tanks on the water coming from the bore hole yet.
 
I had the bore hole water tested about 2 years ago and they gave me a 3 page report that basically said it is good drinking water.

Problem is that in a residential area the quality of the ground water can change very quickly so if I use it for drinking I really need to have ongoing tests done every 3 months.

At the moment I'd rather avoid the considerable expense and inconvenience of doing this hence the complicated split system with council water for consumption.
 
Loving the bends also get some protection on them pipes in the ground some simple waterproof gaffa tape will do

Yea so it's good enough to wash pots, fill toilets etc with
 
Unless everyone locally does the same then the neighbourhood consumption will only drop ever so slightly, so the drinking water will just go off a tiny bit later in May - so then you'll just use bore water for everything then you may as well do it now?
 
Loving the bends also get some protection on them pipes in the ground some simple waterproof gaffa tape will do

Yea so it's good enough to wash pots, fill toilets etc with

The bends are a bit unconventional, I used pipework I had in stock which is a mixture of hard drawn 15mm and 22mm, soft drawn 3/8"refrigeration pipe and 25mm class 6 HDPE so it ended up a bit of a mishmash.

What protection do the pipes need and to protect them from what?

Unless everyone locally does the same then the neighbourhood consumption will only drop ever so slightly, so the drinking water will just go off a tiny bit later in May - so then you'll just use bore water for everything then you may as well do it now?
The domestic consumption in Cape Town has dropped by around 50% over the las 6 months with the water saving campaigns that have been ongoing.

I'd rather not use borehole water for consumption until absolutely necessary because of the high costs involved in the constant monitoring its quality.
 
They look spot on, bending spring ??

Protection from the ground / cement as it can eat into the copper down the road

And water proof gaffa tape is very good also if your going to cement the whole lot in add some insulation to allow for any movement
 
Cool diagram, you don't have fresh water to bathrooms for teeth brushing?
No, the bathrooms are all on borehole water so I'll have to teach wifey to spit instead of swallowing. :D
 
They look spot on, bending spring ??....
The 15 and 22 bends were done with one of these1.jpg

The bends on the 3/8 refrigeration pipe with one of these
2.jpg
I have some spring benders but I've never found them easy to use and be accurate. Probably just need some practice.
 
I hope you have some decent backflow prevention device between the bore water and the incoming council mains.

I mean more than a ball valve and a spring loaded check valve.

You could contaminate the local potable water supply with the setup you have - under certain circumstances.

You might not want to drink bore water - your neighbourhood might not want to also.
 
I have installed a spring loaded brass check valve, I guess I could double up and install two of them. What other type of backflow prevention would you normally install?
 
Funny you should mention backflow because that was one of my questions I have lined up.

My kitchen sink has an old type mixer tap. I've opened up the wall and removed the original pipe to the cold side and installed a new pipe so it can be fed from council water. The hot side of the same mixer tap will be fed with ground water via the hot water cylinder. I figure there's a chance of backfeeding if both hot and cold taps are open simultaneously and the council pressure happened to be lower than 300kPa which is the pressure I'll be supplying the groundwater into the house at.

As much as I don't want even the very remote possibility of poisoning the neighbours I also don't want to have the cost of my borehole running flat out 24/7 to supply the entire neighbourhood if or when day zero arrives and they start closing water supplies to whole suburbs.
 
Ideally you want a bi flow tap (eg the supplies never touch each other until there out the spout)

But you can get away with check valves on both sides/ supplies at point of use
 
Here's a picture of the pipework changes I made to the cold side;

p7.jpg

and this is what the mixer tap looks like;
p8.jpg
 
Ideally you want a bi flow tap (eg the supplies never touch each other until there out the spout)

But you can get away with check valves on both sides/ supplies at point of use
Thanks Shaun.

Is the spout on a bi flow tap segregated all the way through to the point of discharge stop the hot and cold mixing?
 
Thanks Shaun.

Is the spout on a bi flow tap segregated all the way through to the point of discharge stop the hot and cold mixing?

Yes spot on let's say the spout is made out of 15mm tube for this theory it will have another piece of tub eg 3/8 in the centre of the spout

15mm will be the cold and 3/8 will be the hot side, so there is defo no chance of it mixing

Hope it makes sense

IMG_3309.JPG
 
Thanks, it's always good to learn something new.

I wasn't looking to replace the mixer tap and I'm not sure if we'll have the option of bi flow or dual flow taps local to me. Also in the past I've even had difficulty finding the wall mounted mixers, I'm guessing they may be out of fashion nowadays. I'll phone around on Monday and see what the local suppliers have in stock, if it looks like problems I'll probably just go with the check valve option.

I assume you just fit a spring loaded check valve into both the hot and cold pipe. I'm not worried about a bit of crossover from the cold into the hot side, only from the hot to cold which is the only direction that could cause backfed contamination into the council supply....in which case a check valve only on the hot side may suffice maybe.....??
 
Check with your county's rules but yea you could just put a check valve of one supply aslong as there equal pressures
 
There are regs here that you're not allowed to have water flow back into the council supply but I'll play it safe and install two check valves, one on each side of the mixer.
 
I have installed a spring loaded brass check valve, I guess I could double up and install two of them. What other type of backflow prevention would you normally install?

What you are doing would be considered 'High Hazard' to potentially contaminate the potable water supply.
You are going to need at minimum and RPZ Valve, that will discharge any bacflow out a vent.
This will have to be installed upstream of where you connected the bore water to your cold supply
 
I've scoured the internet as well as my off-line catalogue library and RPZ valves or off-loading backflow preventers aren't available here for domestic use. The only similar valves I came across are 6 inch flanged for fire systems and PRV's with integral check valves and a pressure operated off-loading dump outlet which aren't really designed as anti-backflow, more for over pressure safety release for pressurised immersion heaters.

I'd guess the lack of availability indicates the lack of local legal requirement but I'll check up tomorrow to be sure.

Out of interest how much do you pay for RPZ valve backflow preventers? Don't supose you want to mail me one of your surplus ones maybe? :D
 
I must say, design aside, which I'll leave to you and the legislators to decide over, that is tidy work and impressive.

I just hope that you aren't being fooled into thinking this is going to reduce your total environmental impact by a large percentage?
 
Thanks Ric. TBH the plumbing changes I'm making aren't motivated around reducing environmental footprints, it's merely about having water at home if/when it runs out or they start turning off water to whole suburbs for periods of time to reduce consumption.

I looked at several possibilities such as rainwater storage, gray water treatment and storage etc but where I am the rain is very seasonal and the storage volume requirements would be prohibitive on both cost and logistics side for such a system. Gray water treatment on a small scale would be viable but on a larger scale in our climate there's health implications associated with standing contaminated water. The yield to cost ration of such a system would be small

First step was to reduce consumption which was no easy feat with two teenagers in the house. We're down to consuming around 8-10 kilolitres per month (from 20 kilolitres initially) which was achieved by relatively simple measures such as placing a brick in each toilet cistern, installing low flow shower heads and generally educating the family on not wasting amongst other things. It also helped that the council pressure was reduced from around 11-12 Bar static down to 3-4 Bar at present because it was a constant battle with dripping taps and ball float valves overfilling toilets and overflowing.
 
We've had a borehole for around 15 years which I installed myself for garden irrigation. Touch wood it's always delivered water, even in our dry season, at a rate of around 22-25 litres per minute. My cheapest and easiest option was to extend the existing borehole system to supply the house also. I finish my drawing so you can see the system in its entirety;
Bore Hole Water Supply.jpg
 
Getting back to the back-flow issue I'm comfortable that the risk is low and can be managed. When the system is configured so the borehole water is supplying the bathrooms, the hand valve, labeled 'Valve 1' on the drawing above, will be manually closed. I'm happy that the chances of a hand valve on a clean council water supply allowing leakage back through it are minimal. The check valve situated upstream next to it is double protection against it. The only way the risk is increased is if the various valves are wrongly set or opened and closed in the wrong order which is unlikely as I'll be the only person operating them but I'll make up an instruction card and hang it on the manifold as well.
 
Managed to spend a few hours on the water installation today, completed the PRV, filter and pressure tank install and got the pipe to the borehole panel buried and connected. Pressured the system up and fingers crossed no leaks.....yet....

1.jpg


2.jpg
 
Just a tip pressure regulators don't like to be on there side or downwards facing so needs to be turned back to the wall
 
Have you thought through the implications of putting the pump (and other electrical gear) in what looks like a rather well-sealed box. How's the heat that the pump motor will need to need to dissipate going to get out?
 
That panel was already existing, it's a year or more old, it's just the trenching I did yesterday and a new 25mm pipe that I installed to it.
You can't see in the photo but the panel has a 100mm circular cut-out for the air flow on the left hand side where the back of the pump is and there's several.....from memory I think 8 or 10 x 25mm vent holes in the bottom of the panel.

I checked temperatures during the 1 hour irrigation cycle when I built the panel and there was no overheating issues as long as the head pressure was above 2 Bar.

There was one irrigation station back then that was running at very low pressure and the pump got close to its temperature limits when that station was active but I re-jetted the sprinklers to increase the water pressure and increased the run time of that station which solved the problem.
 
Well my system has been up and running since early Jan and our council water consumption is going to be just under 1 kilolitre per month which is great.

I have one slight unforseen issue....more of an annoyance really. The borehole water has some air in it which makes the showers 'spit' every 30 seconds or so when you use them. You can also hear spitting noises in the toilet cisterns as they refill.

I should have really preempted this issue because the irrigation system that was previously running on the borehole also used to make periodic spitting noises but it was never an issue we worried about when it was just irrigation.

The showers however go momentarily hotter or colder when the spitting occurs so it's something I'd like to remedy if it's not too involved or expensive.

So what I need is a cunning and inventive way to remove air from a sealed and pressurised water system, a way that's ridiculously cheap, can be done using the very basic plumbing components we have available off the shelf in far flung Africa and can be installed by a plumbing muppet with zero plumbing tools or experience.

Yeah....not asking for much I know but God loves a tryer....so they say.:)
 
two options but whats your pressure of the pumps / coming out the taps at and flow rate?
 
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