Having Fun With Some DIY Plumbing

[marvoni]

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.

 

[ShaunCorbs]

any pics marvo ?

and did you get the bore hole tested before hand?

 

[marvoni]

Before I start with questions I thought I'd try buttering you up with a few photos first.

New pipework for the coffee machine.

Alterations to the water main coming into the house.

Installing pipework from the bore hole to the house.

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.

 

[marvoni]

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.

 

[ShaunCorbs]

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

 

[neilrj]

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?

 

[marvoni]

Here's a schematic you can compare to the last photo I posted above;

 

[neilrj]

Cool diagram, you don't have fresh water to bathrooms for teeth brushing?

 

[marvoni]

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.

 

[ShaunCorbs]

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

 

[marvoni]

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.

 

[marvoni]

They look spot on, bending spring ??....

The 15 and 22 bends were done with one of these

The bends on the 3/8 refrigeration pipe with one of these

I have some spring benders but I've never found them easy to use and be accurate. Probably just need some practice.

 

[oz-plumber]

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.

 

[marvoni]

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?

 

[marvoni]

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.

 

[ShaunCorbs]

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

 

[marvoni]

Here's a picture of the pipework changes I made to the cold side;

and this is what the mixer tap looks like;

 

[marvoni]

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?

 

[ShaunCorbs]

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

 

[marvoni]

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.....??

 

[ShaunCorbs]

Check with your county's rules but yea you could just put a check valve of one supply aslong as there equal pressures

 

[marvoni]

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.

 

[oz-plumber]

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

 

[marvoni]

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?

 

[Ric2013]

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?