Rainwater (tank water)

[parrankin]

I have some problems getting my head around water chemistry when I live in a country area with reliance upon rainwater from tanks with no idea of the chemical makeup of the water. The water tastes fine and the ph is always around 7. Being in a country area it is an expensive process of buying RO water or distilled water, also getting a water test done is expensive. Does rainwater have chemical profile, or once filtered can it be a clean slate from a minerals perspective. I once had a discussion with people at a brewing shop and give them a sample of my water, they said the ph was 7 so just add a small amount of Calcium Sulphate and all will be good. I'm looking forward to using the calculator and looking into the finer details of profile to the style of beer. Sorry if there is possibly many discussions on this already.. very new to the site! Is it worthwhile investing in an RO filter?

 

[Zambi]

I use river water.
One day I will get around adding chemicals to it.
You can get a cheapish set with paper strips to test the water. Generally rain water should not contain much and I would just use it and consider it "nutrient less"

 

[parrankin]

Yes, agreed.. I have a ph meter now and keep in touch with what's going on from that perspective. However some batches are not as good as I would like, hence looking at the water. Most apps and videos get you to enter your water details to start with .. not knowing where to start!! I guess start from 0,0,0,0 and give it a go.
Sounds like your river water is going ok!

 

[Flying Weasels Home Brewery]

Interesting question! You can get kits to measure mineral content, but it wouldn't be fun to have to test every time.

I asked my local AI if rainwater is generally considered to be very soft, and it said yeah.

Yes, rainwater is generally considered very soft water.

Here's why:​

• Soft water is defined as water that has low concentrations of dissolved minerals, particularly calcium (Ca²⁺) and magnesium (Mg²⁺) ions.
• Rainwater originates from the evaporation of surface water, which leaves minerals behind. As it condenses and falls as precipitation, it is naturally low in mineral content, making it soft.
• However, as rainwater falls through the atmosphere, it can absorb gases like carbon dioxide (CO₂), forming weak carbonic acid, which can make it slightly acidic. This doesn’t make it hard, but it can affect its pH.

 

[Donoroto]

I have some problems getting my head around water chemistry when I live in a country area with reliance upon rainwater from tanks with no idea of the chemical makeup of the water. The water tastes fine and the ph is always around 7. Being in a country area it is an expensive process of buying RO water or distilled water, also getting a water test done is expensive. Does rainwater have chemical profile, or once filtered can it be a clean slate from a minerals perspective. I once had a discussion with people at a brewing shop and give them a sample of my water, they said the ph was 7 so just add a small amount of Calcium Sulphate and all will be good. I'm looking forward to using the calculator and looking into the finer details of profile to the style of beer. Sorry if there is possibly many discussions on this already.. very new to the site! Is it worthwhile investing in an RO filter?

As noted above, rain water generally has few minerals. You will probably want to filter it for particles (as with a simple paper filter), since the whole world has particulates in the air, even if your location does not generate them.

The pH of the water is mostly irrelevant, because it has very little ‘buffering power’, meaning the grain will overwhelm the water pH with its own pH. Adding some calcium (maybe 5 grams in 20 liters) will help.

Also read about the sulphate-to-chloride ratio and its effect on the beer. If you are adding brewing salts, this is something to consider.

 

[Donoroto]

Oh, and an RO filter: probably not now, perhaps if you run into troubles with your water in the future.

 

[parrankin]

Oh, and an RO filter: probably not now, perhaps if you run into troubles with your water in the future.

Thanks for that feedback, I had similar thoughts on the RO filter.. will develop a plan for my next beer, may be a bit of trial and error.

 

[Zambi]

As noted above, rain water generally has few minerals. You will probably want to filter it for particles (as with a simple paper filter), since the whole world has particulates in the air, even if your location does not generate them.

Won't those particles be removed by a grain bed or biab bag?
Or just settle out (and become part of the trub)?

 

[Donoroto]

Won't those particles be removed by a grain bed or biab bag?
Or just settle out (and become part of the trub)?

Perhaps, but I am thinking of very small particles, not visible bits. Think diesel exhaust as an example.

 

[Craigerrr]

Back in the late 80's and 90's acid rain was a big deal, killing lakes and all, but that either isn't an issue anymore, or possibly it never truly was...
Using rain water is an interesting idea, I had never thought of that. At least chlorine, or chloromine are issues you don't need to worry about.
One thing I would point out is that the beginning pH of your brewing water is of no real consequence, it has more to do with the ion make up of said water, and the make up of your grist.

 

[Zambi]

Perhaps, but I am thinking of very small particles, not visible bits. Think diesel exhaust as an example.

Lemme check with my river water.
I'll run some through a coffee filter bag.
Or maybe I shouldn't, I might get scared and never want to use it again

 

[Sandy Feet]

Lemme check with my river water.
I'll run some through a coffee filter bag.
Or maybe I shouldn't, I might get scared and never want to use it again

Does the elephant shit give you enough minerals? LOL

 

[BarbarianBrewer]

I would think that only significant source of contamination would come from whatever the rainwater drains across on it's way to the collection point. I'm thinking of roofs, gutters, trees, etc. Otherwise it's pretty much RO water, isn't it?

 

[Donoroto]

I would think that only significant source of contamination would come from whatever the rainwater drains across on it's way to the collection point. I'm thinking of roofs, gutters, trees, etc. Otherwise it's pretty much RO water, isn't it?

No. The sky is full of particulates, tiny tiny motes of dust. Water vapor needs something to kick off condensation, those motes are them. Almost universally not harmful - think Canadian forest fire smoke, or Sahara sand dust - they’re in every raindrop.

Surface water often has biological stuff, like from heffalumps or other critters, but in concentrations that are generally ignorable. Big rivers have a lot more water, and sunlight is indeed a disinfectant.

@Zambi you might find a slight tinge of mud in your coffee filter, but if it hasn’t killed you (and your neighbors) yet, it’s unlikely to do be a problem.

 

[Dave Y]

Probably a sediment and carbon filter is fine. I toured Roatan Island Brewing; they use well / tap water and their beers were definitely credible.

 

[parrankin]

Thanks for the feedback guys, my process is filter the rainwater through a paper filter then carbon filter then through a uv light thing to kill any bugs. My assumption at the end is it will be very close to RO water. I will go with some standard additions to style and see how it goes for the next beer.