@ Sharon van Tuylen ...

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Sharon van Tuylen

Potential adverse health reactions related to acidic water are related to the potential for high metal concentrations. This can be a major issue in older distribution systems where lead pipes and fittings may have been used, as plumbo solvency can cause harmful concentrations of lead in the water.  Such low pH values may also strip silver nitrate ions form any household filters, reducing their effectiveness in removing bacteriological pathogens and reducing their effective life. High silver concentrations in water can have chronic negative health impacts, but I think this is unlikely to be an issue, as the doses would be low. Silver toxicity is readily identified in any case-it turns the skin and hair blue.

 

At the pH values of 4-5 the carbonate equilibrium will be shifted towards carbonic acid. However I would be concerned that you are getting such a high degree of acidification in the rain, which would indicate some form of atmospheric pollution. If you are in an urban environment you could be getting dry deposition of nitrous oxides (traffic fumes) or there may be a source of sulphur dioxide. Or there could be a build up of organics in your system, with the acid coming from microbial or algal sources.

I would suggest that you check the water for inorganic nitrogen before supply as nitrates can cause health problems-methemoglonemia. This is often associated with vitamin C micro nutrient deficiencies, and can be fatal to children, especially those fed with formula. You would need to check for both nitrates and nitrites-again the equilibrium of these species is pH dependent.

On the positive side you will get very little microbial activity at such low pH, so the water is likely carry low acute risks associated with bacterial and potentially viral pathogens.

In terms of increasing raising the pH, the simplest solution would be to increase retention time in your systems. Carbon dioxide will dissolve into the water, pushing the carbonate equilibrium towards the carbonate end of the spectrum, providing alkalinity and bringing the pH up towards the more normal range of 6.5 to 8.5. If this process is to slow you could try cascade aeration.

 

Hope this helps

 

John Cody