Rain Water, Dissolved Metals

[pdilley]

Inspired by the distilled water post, I thought I would look into rain water as it is now my main water source and I wanted to know what issues could arise with rainwater.

Now my rainwater tastes cleaner and sweeter than any I ever had in Melbourne (S.E. suburbs, N.W. suburbs) and I've never gotten sick or felt under the weather from consuming it so I know I don't a lot to worry about straight off the bat although I could get it tested if I was really worried or having brewing issues I suspected were due to water quality.

I don't want to overly worry anyone about any water contaminants but it is still good to talk about all the possible contaminants to help anyone that is actually having issues with their rainwater.

Of course having clean water similar to distilled water from a brewing point of view gets you a perfect base water to add any water additions to to dial in any water style you wish. A lot easier to add than to remove so its a nice base water.

Rainwater, as it falls on house roofs, is largely free of contamination, either bacterial or chemical. During collection and storage however, there is a potential for this to change. Most contaminants enter through the storage container or the pipes. Lead is the one yeast is more sensitive to, if you can taste iron in your water or see rust in your water your levels are too high. Charcoal filters won't help much here, reverse osmosis is what you will most likely need and you can switch to a distilled water as a test batch to brew if suspecting iron as a culprit.

Water in rainwater tanks can sometimes be contaminated by micro-organisms from animal faeces. Bird and possum droppings are the most common. As water is boiled during making beer bacterial levels are not a worry. Drinking bacterial contaminated water however, you will worry.

Chemical contaminants can be present in airborne dust. Sources include car exhaust fumes and agricultural/industrial chemical emissions. Lead based paints or flashing used on some older roofs may also flake off. All these contaminants can be washed from roofs into rainwater tanks. The common chemical contaminants in rainwater are iron, lead, zinc and copper. Acidity or pH and salinity are also tested to provide an idea of the general water quality.

The top five are listed below,

::Copper::
Issues: Taste, Staining, Health
Health Guideline: 2mg/L
Aesthetic Guideline: 1 mg/L
Source: From corrosion of pipes/fittings by soft, low pH water. Taste threshold 3 mg/L. High concentrations colour water blue-green. Greater than 1mg/L may stain fittings. Greater than 2mg/L can cause ill effects in some people.

::Lead::
Issues: Health
Health Guideline: 0.01mg/L
Aesthetic Guideline: N/A
Source: Occurs in water via dissolution from natural sources or household plumbing containing lead (e.g. pipes, solder).

::Iron::
Issues: Taste, Staining
Health Guideline: N/A
Aesthetic Guideline: 0.3mg/L
Source: Occurs naturally in water, usually less than 1mg/L but up to 100mg/L in oxygen depleted groundwater (wells, bores, etc.) Taste threshold is 0.3mg/L. High concentrations stain laundry and fittings.

::Zinc::
Issues: Taste
Health Guideline: N/A
Aesthetic Guideline: 3mg/L
Source: Usually from corrosion of galvanised pipes/fittings and brasses. Natural concentrations generally less than 0.01mg/L. Taste problems at greater than 3mg/L.

::Nickel::
Issues: Health
Health Guideline: 0.02mg/L
Aesthetic Guideline: N/A
Source: Drinking water usually contains very low levels of nickel. Long term exposure may result in toxic effects to the kidneys. Nickel is known to be a common skin allergen and can cause dermatitus particularly in younger women.


Cheers,
Brewer Pete

 

[Wolfy]

Rainwater, as it falls on house roofs, is largely free of contamination, either bacterial or chemical.
...
Water in rainwater tanks can sometimes be contaminated by micro-organisms from animal faeces. Bird and possum droppings are the most common. As water is boiled during making beer bacterial levels are not a worry. Drinking bacterial contaminated water however, you will worry.

Looking at all the airborne pollution around Melbourne, are you sure that a large-ish amount of that does not collect in the rain and fall back down to be concentrated in tank-water?
I thought I remembered some health warning (or it could have just been one of those stupid today-tonight type TV shows) now that every 2nd person has a tank in their back yard, that the rain-water is not as safe as they thought due to heavy metals and the like.

True about the animal crap though, but I grew up on tank water, 2 open tanks, open roof gutters, no filtering of any kind, always drank it straight from the tap for many years ... still alive today.

 

[pdilley]

I'm out in the boonies with 600 people living in the place and am far far away from Melbourne. Not sure I would drink rain water if I was living and collecting in Melbourne, but out in the country so I don't mind that much. It will be more of an interest to see how my water affects my brewing and then adjust as needed as I've been so used to my previous water profile.

You can always get the water tested, I only had my bore water tested not the rain tanks, if you want to worry less.

Edit: Yes, about the crap. The nitrates feed the bacteria that clean it up in the water and clean the water anyway. Much healthier to not live in a sterile environment.

Edit2: Out here, television is going digital and the antenna guy tested all signal points and we are 10 dB too low, even with amplifiers hooked up to get digital TV so its a life of beer, brewing and book reading for me. They also called my area a black spot, but I had a special YAGI put up and now get Internet so I'm not fully disconnected from the world (not that something like that would necessarily be a bad thing.)

Cheers,
Brewer Pete