Rooftop rainwater to concrete tank and espresso?

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
Maak

#1: Post by Maak »

Hi. I moved to a rural location and have a plumbed machine. I find many articles about city water or recipes for unplumbed but not for tank water. Rainwater comes off several roofs and we have two concrete tanks.

I'm using the same type of omnipure filter I was using in the city and wondering how to check if it's right for the water here. The water tastes great and no chems are added.

ira
Team HB

#2: Post by ira »

I would wonder if the concrete tank causes high hardness? If it rains reasonably often and you can save some of that water to 5 gallon glass bottles, that might be a good solution.

Nunas
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#3: Post by Nunas »

Maak wrote:Hi. I moved to a rural location and have a plumbed machine. I find many articles about city water or recipes for unplumbed but not for tank water. Rainwater comes off several roofs and we have two concrete tanks. I'm using the same type of omnipure filter I was using in the city and wondering how to check if it's right for the water here. The water tastes great and no chems are added.
When we lived aboard our motor yacht, we caught rain on the monkey island and, once the first bit of rain had flushed the roof, directed it to our holding tanks. It was really soft water, and we drank it routinely with only a simple particulate filter, followed by a carbon filter. So, we know that rainwater is soft, and we didn't suffer any odd maladies :) . Now, we held our water in two 1900 litre stainless tanks, which kept the water soft, whereas you're holding yours in concrete tanks. I have no idea what happens to soft water stored in concrete tanks, apart from vaguely recalling that doing so does not guaranty that it remains potable. So, my purely anecdotal analysis of your situation only as it concerns espresso making, would be that a simple test with a cheap TDS meter would soon enough give you a rough idea whether the water remains soft enough to not scale your machine. As for being drinkable in espresso, I've no idea if heating the water in an espresso machine would kill any pathogens. I hasten to add that we shocked, drained and refilled our tanks once a year, and cleaned them thoroughly on every haul-out.

Edit: I got curious about holding potable water in concrete tanks and found this https://westconprecast.com/precast-prod ... -cisterns/ I think you're probably good to go! Subject, of course, to routine cleaning and sanitizing.

Pressino

#4: Post by Pressino »

The following website (from the same region of the globe as the OP) includes a good discussion of collected rainwater as regards its hardness after exposure to things like roof tiles and concrete tanks: http://www.lanfaxlabs.com.au/hardness.htm

Apparently small amounts of Ca++ and Mg++ can leach out of the concrete for the first year or so, it seems even then not so much to be a problem for espresso boilers. And afterwards not really a problem at all. It's also likely that the rain water will contain enough dissolved solutes that it might not need the addition of stuff to make the boiler level sensor work or prevent metal corrosion from use of "pure" water.

BTW, I think in the USA Hawaii has lots of homes that use collected rainwater.

Maak (original poster)

#5: Post by Maak (original poster) »

Pressino wrote:Apparently small amounts of Ca++ and Mg++ can leach out of the concrete for the first year or so, it seems even then not so much to be a problem for espresso boilers.....
Yeah..it's just how much is too much on regards to espresso. Taste especially..I guess I should test it.

Here in NZ most rural houses away from town water suply have rainwater tanks. All older ones are concrete and newer ones plastic (because they're cheaper but not as good.) Ours are 30 yrs old but that's not old for water tanks here.

The espresso machine is plumbed and had been working for a few years (with filters) but I'm getting a whole house filter and purification system and wondered if anyone knew anything specific that would suit this situation in regards to espresso machines and espresso water.

Rain water is soft and slightly acidic. The concrete tank apparently makes it a bit harder and slightly alkaline. Our water doesn't seem hard but I'll get it tested as a simple tds will not be specific enough.

Maak (original poster)

#6: Post by Maak (original poster) »

Now I have an Answer.

I bought a GS3MP and took a water sample in to Lamarzocco NZ for them to test. A reasonably good test I'm told, better than the test strips thast come with the GS3
Turns out rainwater in a concreet tank is super alkaline. So much that its off the scale.
Turns out that its also super soft. So much so that its off the scale.
There are no salts or minerals, which makes sense as rainwater is essentially distilled
I was told I could not use this water and be covered for warranty.

So temprarily I'm using a local bottled water wich has LM aproved specs but wil get a filter with remineralizer

Pressino

#7: Post by Pressino »

Very revealing. The link I provided above didn't really address the problem of alkalinity of water stored in concrete tanks, and that appears to be the main concern cited by La Marzocco. They also found that there are essentially no dissolved minerals, which makes sense for pure rainwater, but I'm surprised none leached from the concrete walls of the tank.

From what La Marzocco says, it sounds like you have what amounts to RO or distilled water from your tank. Maybe the easiest way to deal with that would be to treat it just like RO water and reconstitute it with "machine safe" minerals and adjust the pH as needed.

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homeburrero
Team HB

#8: Post by homeburrero »

Maak wrote:Turns out rainwater in a concreet tank is super alkaline. So much that its off the scale.
Turns out that its also super soft. So much so that its off the scale.
There are no salts or minerals, which makes sense as rainwater is essentially distilled
I was told I could not use this water and be covered for warranty.
Thanks for reporting back. I'm a little perplexed as to how it might end up with very high alkalinity and very low hardness. Any chance you can share some actual numbers from that LM NZ analysis?
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

Maak (original poster)

#9: Post by Maak (original poster) »

Sorry I should have said off the scale LOW alkalinity

DeuxInfuso

#10: Post by DeuxInfuso »

Maak, low alkaline (acidic) and super soft... sounds like rainwater!

Basically the same as distilled or RO water. Just add a pinch of sodium bicarbonate (baking soda) per liter. A fat pinch maybe. It isnt a fussy recipe. You won't taste it at all.

Raises pH to about 7.5 above neutral, just slightly alkaline. Or use potassium bicarbonate, sold as electrolyte supplement at drugstores. Look up Dr R.Pavlis water recipe, lots of info in the water forum. Add 0.10 gm/liter for 100 ppm. Or 0.38 gm/gallon. Entirely non-scaling if there's no Ca or Mg, and no need to descale, ever. Makes great tasting coffee.