I just got off the phone with someone from the HSE who tests water supplies in the Kildare region. She gave me a bang up to date profile for areas served directly by the Poulaphouca Reservoir (see values below).
She seemed very proud of this water source and kept emphasising how good the quality of the water is for those directly supplied by the reservoir. And because there is no mixing with other water sources, the readings stay pretty stable throughout the year (which confirms the results I always get when I test my own water myself).
Poulaphouca water is quite soft because it flows over granite, not limestone, such as happens in the water around Leixlip for example. So it's ideal for pale beers, though still requires calcium additions for good enzyme reactions and yeast health etc.
Ok, enough blather. Here's the values:
- Total Hardness (TA - as expressed in CaCo3): 60
- pH: 7.8
- Magnesium (Mg): negligible (she estimates it to be 1 or 2ppm)
- Calcium (Ca): around 20
- Sulphate (SO4): 22.4
- Chloride (CI): >15 (somewhere around 13 or 14 she estimates)
- Sodium (Na): >6 (i.e. negligible)
There were no readings available for bicarbonates (HCO3) or total alkalinity (TA) but I think these can be worked out from the other figures. She's sending me out a hardcopy of the figures on Monday so I'll be able to confirm all the details then.
This is the water that Rossa brews with and wins competitions. When I asked him how he treats his water,he said all he does is toss in a bit of gypsum and a pinch of epsom salts,the fecker. :)
For pale to amber beers that's all you'd need to do really. I don't know if Rossa gets his water in pure form from Poulaphouca or as a blend with another supply, but if simple calcium additions are doing the trick his water must be pretty similar.