Is acidic water an issue with all plastic/stainless?

[sam]

We have slightly acidic spring water (pH 6) which currently passes through a neutralising cylinder. 

 

We are replacing our plumbing pretty much in it's entirety and will have a stainless hot water cylinder and can have plastic pipes. We will therefore have very little copper.

 

I already have the neutralising cylinder but it does take up space and need servicing. I'm aware that acidic water can make your hair green, but otherwise I'm wondering if there are good reasons to keep the neutralising cylinder in the system? I like to make things simpler if I can.

 

[Jeremy Harris]

I'd very definitely keep the pH neutralisation system in place.  What sort of system are you using, just a pressure vessel filled with limestone chippings, or something that needs regular maintenance?

 

A simple pressure vessel filled with limestone chippings, with a bypass and valve to adjust the pH to 7, should last a long time before the chippings need to be replaced.  If you fit two vessels, so you can change them over and refill one whilst the other is in service, it's easier to look after.

 

The key to getting a long interval between services is to size the system correctly and set up the bypass accurately, so that the pH is spot on 7, and no higher.

[sam]

Thanks for the quick reply.

 

It's a blue pressure vessel filled with limestone with bypass values and an automatic backwash on a timer.

[Jeremy Harris]

Backwashing will undoubtedly deplete the limestone more quickly unless it's necessary to clean the chippings or other neutralising media of something like ferric iron deposits.  A simple pH correction system only really needs the vessel with the limestone plus the bypass, unless you've also got something like dissolved iron in the water that accumulates as iron salts in the media and so has to be periodically washed out.

 

Do you have an analysis for the water before treatment?  If so that should indicate what else is in the water.  It's not uncommon to have excessive amounts of ferrous iron in solution in acidic water, and some of this will drop out of solution as insoluble ferric iron as the pH increases, and so build up in the vessel, needing the backwash.  The safe drinking water upper limit for dissolved iron is 200 µg/litre, so may be your water would have more iron in that this if it wasn't pH corrected.

[sam]

That's interesting, thank you.

 

Someone told me that the backwash was required to 'mix' the limestone so you didn't get channels forming and to prevent it to solidify into a block.

 

I've not had it tested for iron or anything other than pH. I guess you need to send this off to a lab to do - does anyone have a recommendation? The spring water is pH 6 and the system only corrects this to 6.5 at the moment.

 

The spring has been used at least since the 1950s but the pump, partial filter, UV filter and neutralisation system were only installed last year, before we purchased the house. It's almost a year old now and hasn't been serviced, other than me physically cleaning the partial filter.

[Jeremy Harris]

A pH of 6 is actually within limits, but probably makes the water taste slightly acidic, but TBH I doubt it'd be enough to notice.  I suspect that the pH correction system was put in to fix something else, like a high dissolved metals problem, rather than just to provide a very modest correction to the pH.  In general, most metals are more soluble in acidic water, and some metals are not great for health.  The worry isn't with your plumbing, as very little copper is going to dissolve into water at a pH of 6, it's with whatever metals are in the ground that the aquifer feeding the spring runs through.  Here are the UK acceptable limits for minerals and metals in drinking water (there is zero tolerance for coliforms, cysts etc, which are pretty much bound to be present in water from a surface spring, but the UV will kill them off as long as it has a 5µ pre-filter):

 

 

There are lots of labs that will do a water test, but often it's cheaper to get your local environmental health people in the council to come out and take a sample and get it tested.  They have a capped price (around £125 here) to do this and that is cheaper than the majority of labs would charge - I found that labs charged over £150 just to test a sample that I'd taken myself.

 

There's no mandatory requirement for testing a private water supply, as long as no one other than the householders use it.  The moment you allow the water to be used by others (for example paying guests at a B&B) then there is a mandatory requirement for annual testing.

 

In terms of servicing, the UV tube needs replacing every 12 months, although they seem to last around 18 months in practice.  Some UV systems have an alarm that goes off to remind you to replace the lamp, or if the lamp fails.  UV lamps are bloody expensive, and I found that it's a lot cheaper to buy them in bulk direct from China (where most of them are made anyway).  At the same time as the lamp is changed the 5µ pre-filter needs to be changed or cleaned.  I used a washable pleated pre-filter and have two, so I can swap them over and then wash the spare ready to be swapped back the next year.

 

Channelling is only an issue with filter media, not with limestone chippings for pH correction, so that makes me think that you've either been given duff info or the thing is doing more than just a little bit of pH correction. 

 

[sam]

Thank you for the useful reply.

The system was last serviced with Juraperle which is 99.4% calcium carbonate. A friend suggested a more economical option was to purchase bird grid of the appropriate size.

 

I spoke to the company that serviced the system (it was in fact installed earlier than I had thought by a different company) who explained that they would recommend installing a pH neutriliastion on the grounds of pH 6, so there may or may not be a dissolved metals problem. I have a water analysis report but it is after treatment and shows everything within acceptable ranges. They were in favour of the back wash system saying it 'agitated' the contents.

 

Do you mind sharing the detail of the company you buy your UV bulbs from? 

[Jeremy Harris]

For UV lamps buying in bulk from these people is around half the price of getting them from any UK supplier I found, and the lamps they supply seem to be very good: http://www.uvebay.com/

 

For pH correction media it's hard to beat the service from GAPS Water, who are really helpful and have a tame chemist to consult.  They may not always be the cheapest, but I've found their service and advice to be second to none: http://gapswater.co.uk/

 

They do a range of pH correction media here: http://gapswater.co.uk/acatalog/copy_of_pH_Neutralisation_Systems__To_increase_pH_.html

 

Juraperle seems ideal for your conditions, but I'm still not convinced there's a need for backwashing unless there are dissolved metals like iron and manganese in the spring water.  Channelling is a problem in fine sand filters, that reduces filtration effectiveness, but isn't a problem with something like Juraperle, AFAIK, and anyway you're not using this as a filter.  I can't see any benefit in agitating the media unless you really need to wash out insoluble metal salts.

 

Gaps sell just the Juraperle media here, in 25kg bags: http://gapswater.co.uk/acatalog/Juraperle--pH-correction-media--25-kg-x-10-6934.html#SID=698  I'd not risk using bird grit, as you really have no idea what's in it - it may be fine for birds, but what else might be in it as a potentially harmful contaminant?

[Fallingditch]

On 14/07/2018 at 09:36, JSHarris said:

 

There are lots of labs that will do a water test, but often it's cheaper to get your local environmental health people in the council to come out and take a sample and get it tested.  They have a capped price (around £125 here) to do this and that is cheaper than the majority of labs would charge - I found that labs charged over £150 just to test a sample that I'd taken myself.

 

 

My LA was not very helpful in regard to organising a borehole test.

 

I found a private testing company known as Lancrop or Yara based in Pocklington, Yorkshire. Their principal market is a range of tests for the the farming community.  However they do offer a standard SA4 Borehole Test for £55.00 + VAT (SA4).  All done by post and very efficient.

 

For interest, my results were:

 

Analysis Result
pH 7.1
E.C. (mmhos/cm) 1.13
Total Alkalinity (mg/l) 288.1
Hardness (mg/l) 395
Total Hardness (mg/l) VERY HARD
Turbidity (Units) < 4
Nitrate N (mg/l) 4.52
Nitrite N (mg/l) 0.014
Chloride (mg/l) 147
Fluoride (mg/l) 0.3
Calcium (mg/l) 113
Magnesium (mg/l) 27
Sulphur (mg/l) 53
Aluminium (mg/l) 0.001
Copper (mg/l) < 0.05
Iron (mg/l) < 0.1
Lead (mg/l) < 0.01
Manganese (mg/l) 0.61
Zinc (mg/l) < 0.01
Coliform Count (no/100ml) 0
E Coli (Beta G Pos) (mpn/100ml)  0
TVC 22C (in 1ml) 0
TVC 37C (in 1ml) 0

 

 

[Jeremy Harris]

That's a very good price for water testing, much cheaper than the nearest commercial lab to us.  That's also really hard water you've got!

 

The LA have a legal obligation to provide a water testing service for private water supplies, so cannot dodge it.  Private supplies that feed more than one house, or that feed something like a bed and breakfast or hotel, have to be annually tested, I believe, and the LA also have an obligation to do this (and charge for it).

 

I found that our LA were reluctant to do a water test, though, as the government have capped the actual test price they can charge to a level that is less than the LA has to pay a lab.  As a consequence, our LA will not accept samples of water for testing, they insist on coming out and taking the sample themselves.  By doing this they can charge for taking the sample, which is the lion's share of the £125 we paid.  BC wanted to see a certificate from the LA Environmental Health people to sign off our build, so we didn't have any choice by to pay.