Off-grid water treatment

[saveasteading]

With no mains water possible, we will be installing a rainwater harvester.

(The harvester system is not the issue, as have done two, but with mains also available)

 

I know we have to treat the water for drinking and for basins, showers, and baths, but not the first thing about how to do it.

Then is it worth splitting the plumbing into treated and raw, to reduce the load on the treatment process?

Wondering also if some harvesters are made of plastic that is not suitable.

[SteamyTea]

Our old mate, Jeremy Harris, made up his own water treatment system for his borehole.  Was basically a sand filter and then bubbling ozone though the the pressurised part.

I think he found out most of his stuff from the USA, where they use boreholes a lot.

 

Can you get enough rain that is storable in reality?

[joe90]

No point in treating water to flush your toilet  etc. Someone I knew was a medic in darkest Africa and when asked about his house in England they could not believe we shit in drinking water!!!!!?

[nod]

20 minutes ago, joe90 said:

No point in treating water to flush your toilet  etc. Someone I knew was a medic in darkest Africa and when asked about his house in England they could not believe we shit in drinking water!!!!!?

Probably answer of the day ?

[Phaedrus]

Even in Highland I would be wary of relying on rainwater harvesting for all your water needs.  Usually the systems are restricted to washing machines, toilet flushing and outdoor use and have a mains top-up which kicks in when the storage tank drops below a certain level.  You could mimic this with a borehole supply with the water treatment downstream of the diversion to the rainwater tank.  Have you done any investigation into the feasibility of a borehole?

[SteamyTea]

I am sure I posted up some other stuff.

[saveasteading]

Thanks all. I have searched Buildhub,  but not found anything on treatment yet, hence my query.

Cost wise, it will be down to whether it is economical to treat the water (then treated goes everywhere) or expensive, and we split to 2 plumbing systems.

Isn't it simply a filter or two, and a UV lamp?

The water will be very clean, with just the odd bit of much-dissolved bird-poo to get rid of or treat. Most mains water has had this content and much worse.

 

Water supply. I will do the sums on capacity. I plan to collect every drop of water from the roof, and not to have the type of harvester that diverts 10% for cleaning purposes. 

Had a big harvester for an office we built and used (25 persons average).   500m2 of (metal) roof to 10m3 tank. Mains to necessary sinks, showers etc, rainwater to flush and outside taps. Water bill was £60/annum including standing charge.

I think the secret of success was catching lots of water when it came. ie big tank and no waste.

Domestic use is different of course.

 

We have the right to piped water from a faraway spring, and it feeds a nearby house. The pipe on site does not work at present and we haven't worked out where the block is. Might be difficult or impossible to resurrect. We need to investigate the costs and options. It will freeze, but should be available to top-up in summer.

 

We are not considering the ample burn, except highly filtered in emergencies, as it has had an interesting journey when it reaches us.

 

Will definitely look into borehole, and the ground looks great for it (sand and gravel). Cost is a concern, but will save £6k and treatment costs from harvester.

If the borehole isn't viable, I expect the borehole companies can supply treatment for rainwater.

 

Any ideas on borehole costs?

[SteamyTea]

4 minutes ago, saveasteading said:

Isn't it simply a filter or two, and a UV lamp?

Basically yes, but the devil is in the detail.

There is the ph of the water to consider, dissolved nitrates, viruses, bacteria, pollen.  Then, depending on what you roof is made from, other dissolved chemicals.

Rainwater is not distilled water.

[Bitpipe]

Founder member Jeremy Harris @Jeremy Harris detailed all of this on his blog but that has gone from its original location, however it is available on the wayback machine!

 

https://web.archive.org/web/20200926232400/http://www.mayfly.eu/2016/07/part-forty-two-water-treatment/

 

A borehole will incur mobilisation cost and a per metre element until you arrive at water.

 

Jeremy built a DIY treatment plant, he had some specific issues to deal with (iron?) but said he found useful information on US and Australian websites.

 

He had a number of challenges, not least incorrect recording of the borehole depth (he had gault clay I recall)  which caused a lot of confusion as he believed that it was deeper than it actually was.

Edited May 19, 2021 by Bitpipe

[SteamyTea]

13 minutes ago, Bitpipe said:

He had a number of challenges, not least incorrect recording of the borehole depth (he had gault clay I recall)  which caused a lot of confusion as he believed that it was deeper than it actually was.

And the boring machine broke down, and then the replacement had the wrong diameter heat in it.

Held him up for a year.

 

The Ozone treatment was elegant though, basically a vertical clear tube with an air release valve at the very top.  Pressurised water was pumped though it, ozone introduced at the base, that reacted with just about everything in it, then the untreated O₂ blead out the air release.

All cheap parts as well.  And being a clear tube, you could see the iron oxide at the base.

[Cpd]

5 hours ago, saveasteading said:

We have the right to piped water from a faraway spring, and it feeds a nearby house. The pipe on site does not work at present and we haven't worked out where the block is. Might be difficult or impossible to resurrect. We need to investigate the costs and options. It will freeze, but should be available to top-up in summer.

This would be my first line of investigation mdpe pipe is not expensive - how far away - a small digger will dig an awful lot of trench in one day. 
I treat my own spring water with particle filters at 10 micron and then 5 micron and then UV it’s a very cheep instal as my water quality is so good already it’s more belt and braces as I rent out accommodation and it’s a requirement from council. There are grants of about £800 per household from council. 

[saveasteading]

This would be my first line of investigation mdpe pipe is not expensive - how far away - a small digger will dig an awful lot of trench in one day. 
I treat my own spring water with particle filters at 10 micron and then 5 micron and then UV it’s a very cheep install as my water quality is so good already it’s more belt and braces as I rent out accommodation and it’s a requirement from council. There are grants of about £800 per household from council. 

 

Excellent, thanks.

50m but through neighbours ground.

Do you have to treat yours for ph ?  We now have a report that says the water is acid (comes from a hillside so not surprising) and needs adjustment to suit health requirements for drinking water. That also limits corrosion of metal parts.

There is very little pressure, having been to a holding tank where our connection is made,  so will need either an inline pump, or taken to a new tank with pump.

We will have the same principle re visitor health as you mention, as we will all get used to the water, and visitors might be sensitive.

 

 

 

 

 

[Cpd]

2 hours ago, saveasteading said:

Do you have to treat yours for ph ?

No the results were really very good, it’s a deep water spring that comes out at the top of a hill ! 
 

[Thedreamer]

3 hours ago, saveasteading said:

 

50m but through neighbours ground.

 

 

 

 

 

 

 

Are your neighbours not prepared to allow you to a dig a trench?

[saveasteading]

Not at that stage but don't foresee any problems. 

I am comfortable with the collection side of it all, but  trying to get ahead with the treatment questions on which I know nothing.

[Cpd]

I used this company for my kit

 

James Rolland
Sales Director (Commercial/Trade)

https://www.gmautoflow.co.uk/

 

They were helpful and the kit was top quality and reasonably priced. 
I have no connection at all beyond being a happy customer! 
I already had a good idea of what I needed as council had already done a survey so it was just a matter of asking them to provide me with the equipment that would satisfy the council’s requirements. 
 

 

 

 

 

[jamieled]

Highland pump centre in Inverness are also useful for treatment kit and advice.

[Gus Potter]

Hi SaveaSteading.

 

Your approach is much appreciated and interesting. Hope this helps.

 

On 19/05/2021 at 12:18, saveasteading said:

Thanks all. I have searched Buildhub,  but not found anything on treatment yet, hence my query.

Cost wise, it will be down to whether it is economical to treat the water (then treated goes everywhere) or expensive, and we split to 2 plumbing systems.

Isn't it simply a filter or two, and a UV lamp?

The water will be very clean, with just the odd bit of much-dissolved bird-poo to get rid of or treat. Most mains water has had this content and much worse.

 

Water supply. I will do the sums on capacity. I plan to collect every drop of water from the roof, and not to have the type of harvester that diverts 10% for cleaning purposes. 

Had a big harvester for an office we built and used (25 persons average).   500m2 of (metal) roof to 10m3 tank. Mains to necessary sinks, showers etc, rainwater to flush and outside taps. Water bill was £60/annum including standing charge.

I think the secret of success was catching lots of water when it came. ie big tank and no waste.

Domestic use is different of course.

 

We have the right to piped water from a faraway spring, and it feeds a nearby house. The pipe on site does not work at present and we haven't worked out where the block is. Might be difficult or impossible to resurrect. We need to investigate the costs and options. It will freeze, but should be available to top-up in summer.

 

We are not considering the ample burn, except highly filtered in emergencies, as it has had an interesting journey when it reaches us.

 

Will definitely look into borehole, and the ground looks great for it (sand and gravel). Cost is a concern, but will save £6k and treatment costs from harvester.

If the borehole isn't viable, I expect the borehole companies can supply treatment for rainwater.

 

Any ideas on borehole costs?

 

The geology of the Highlands is unique and fascinating. Here are some avenues and my thoughts on how you could continue to explore this. Some may well not apply to you but BH is a journey!

 

Say you look at this in the context of a two supply system. One supply is for the bogs and watering the plants when the good dry weather comes, the other for drinking / washing water.

 

You mention an ample burn and that it may have a journey before it gets to you.. say past a few silage pits, crofts and other folk's septic tanks ,which have yet to be upgraded. If many of the old septic tanks etc upstream have been upgraded (wishful thinking) this only tends to reduce the BOD (biological oxygen demand) but not the pathogens and other undesirable chemical compounds so much.

 

However, the water that falls on your garden will generally make its way to the burn . You could maybe dig a relatively shallow trench that intercepts the surface ground water flow in your garden as it travels towards the burn. In other words your garden acts as a partial filter.

 

In a dry summer it may be that the flow is reversed to some extent. Here your garden would act to partially filter the water as it makes it's way from the burn to the trench. In other words during a dry summer you still get more rain on the higher ground so even if your water table drops locally in your garden you can still draw off a sensible amount of water from the burn. When the next winter comes the flow is reversed back to the burn so your garden filter could be "self cleaning". This is how a sand filter in a sewage treatment plant works to some extent.

 

I digress a bit here but it's worth a mention for other BH members too.

 

SUDs requirements. There are a good few posts on BH about this and folk are aware that it relates to say flood prevention. However, there is another aspect to this. If you have dry spell of weather then contamination can build up on your roof. Many industrial buildings have roofs that are plastic (say) coated and the UV sun rays degrade this. Also, you get birds nesting and so on.  If you then get a short burst of rain you wash a high concentration of contamination into a burn / stream that is at a low flow level. You don't get the dilution and this kills the fish and other organisms.

 

Saveasteading.. the same principle could apply in your case. If you are on the West coast of Scotland you'll get more frequent rain.. but the East can be very dry for a few months. If you can find a way of storing enough drinking water/ washing for the dry months then you could in principle be drinking the best water in the world!

 

Once you work your way through this then you can weigh up the economics / practicality of boreholes / spring supply (reliability / security of supply as not on your land) vs say harvesting.

 

Have a look at how you can get rid of your waste water.

 

Mortgage.. maybe some lenders will pick up on the fact that you have an unusual scheme. If you present a good technical case and compare with say a bore hole that may choke up in ten / twenty years time then it's food for thought. One avenue is to show that your scheme complies with the current regs, say in terms of a potable supply of water. From a pratical point of view if your borehole pump breaks down then they are nearly impossible to recover.. I have seen them stuck fast after a few weeks!

 

You often can't get them back out and you have a cable in the way plus a steel recovery wire, try getting a same sized pump back down the same hole!

 

You could get all this to work out with a fair wind.

 

If you wish then post more info about what you know about the ground, the slope, geometry of your plot ect. Your geotechnics and topography could well be a key here to getting this to work.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited May 20, 2021 by Gus Potter
Left handed typo

[saveasteading]

Very helpful thanks all. I will set this aside until I have seen and considered the spring (on someone else's land but entitled to use) the existing pipeline and all else.

In order of current intentions: revised.

1. Spring water, subject to infrastructure. It will need a pump and treatment. Risk of freezing, although we are told it doesn't.

2. Rainwater, using proprietary tank and pump, and added treatment.

3. Own collection system as Gus idea. The most fun perhaps. (the site maps and plans shows a 'well' which apparently means spring, but is nowhere to be seen.)

4. Borehole because of cost and risk of problems.

[Hastings]

@saveasteading Would appreciate any progress info on this subject as I am working on a rainwater-only supply. My system needs a risk assessment and approval by the council - a condition on my planning approval.

 

Rainwater doesn't seem to need much serious filtering compared to most boreholes and surface/burn waters in these parts. They often fail on levels Iron/Manganese and colour. To pass regulations, as well as the usual UV and sediment and perhaps carbon filters needed for all types of source, the key things for rain water seem to be

• pH probably needs raising a little (there's a filter that)
• care to remove particularly organic matter before storage to prevent stagnation (anaerobic decomposition).
• prevention of bird excrement (dissolved chemicals can't easily be removed later by filters) - can be solved by fitting bird spikes on the roof ridge.
• a first flush device discards the first few litres collected (think mini pre-tank)

I don't think for me that it will be worth having separate plumbing for toilet flushing as the house is only 1.5 bedrooms and there would be little or no saving in the filtering costs (we have no mains available).

 

 

 

 

 

Edited February 11, 2022 by Hastings

[Nickfromwales]

28 minutes ago, Hastings said:

@saveasteading Would appreciate any progress info on this subject as I am working on a rainwater-only supply. My system needs a risk assessment and approval by the council - a condition on my planning approval.

 

Rainwater doesn't seem to need much serious filtering compared to most boreholes and surface/burn waters in these parts. They often fail on levels Iron/Manganese and colour. To pass regulations, as well as the usual UV and sediment and perhaps carbon filters needed for all types of source, the key things for rain water seem to be

• pH probably needs raising a little (there's a filter that)
• care to remove particularly organic matter before storage to prevent stagnation (anaerobic decomposition).
• prevention of bird excrement (dissolved chemicals can't easily be removed later by filters) - can be solved by fitting bird spikes on the roof ridge.
• a first flush device discards the first few litres collected (think mini pre-tank)

I don't think for me that it will be worth having separate plumbing for toilet flushing as the house is only 1.5 bedrooms and there would be little or no saving in the filtering costs (we have no mains available).

Rainwater is category 5, which is about as bad as it gets in terms of its introduction into a residential dwelling where it can come into contact with / affect the health of humans.

Im currently installing a RWH system, and the list of criteria to bring water for WC flushing and a washing machine is minimal in fairness ( 3 stage filtration with the facility to back-wash etc ) but in terms of it being ANYWHERE near potable systems then it’s a totally different ball game. 
To have the cold mains refill facility, eg a point where RWH and potable supplies converge, you need to fit double check valves to the cold mains fill point, have a 37mm ( A / A air break ) gap and label up accordingly, and that’s just for toilets snd washing machine.

Borehole not an option? 

[SteamyTea]

8 minutes ago, Nickfromwales said:

Rainwater is category 5, which is about as bad as it gets in terms of its introduction into a residential dwelling where it can come into contact with / affect the health of humans

Going to keep my mouth shut next time I am out in the rain.

[ProDave]

Each time I read this, I wonder how our relatives in Australia survive with Rainwater as their only source of water for everything * and how when we visit and drink the foul polluted liquid we don't even get a dodgy tummy

 

* If the dry season goes on too long they can buy in a tanker of water to keep them going

[Hastings]

41 minutes ago, Nickfromwales said:

( 3 stage filtration with the facility to back-wash etc )

 

What is the backwash filter you are using? Only ever heard of those for use in borehole and other supplies.

 

I have a borehole but the cost of treating (if it can be achieved at all) looks almost as much as an entire new rainwater only system but will not require nearly so much power or consumables (mainly salt) or leave sodium in the water (bad for babies and some diabetics).

[Hastings]

2 minutes ago, ProDave said:

Each time I read this, I wonder how our relatives in Australia survive with Rainwater as their only source of water for everything * and how when we visit and drink the foul polluted liquid we don't even get a dodgy tummy

 

* If the dry season goes on too long they can buy in a tanker of water to keep them going

 

I think the penny is beginning to drop over here. I've heard of one or two houses in Argyll & Bute being okay'ed by the council for entirely rain water private supplies. I just wish I could get the tech details of them (so I don't have to re-invent that wheel).