Last minute questions before using the water...

So we have a metal roof that feeds into two old maple syrup barrels. Each barrel has a sizeable first flush allowance and then a pipe coming out the side that takes the water down into two 1000L IPC totes in our basement. Both totes, prior to getting them into the basement were filled with water and a kilo of baking soda added and left for at least 24 hours to steralize before draining them out and getting them into the basement where they have been kept out of the sun while we worked on the adding new floors to our building. We now have waste plumbing in place for our kitchen sink and our washing machine and are about to get the pump connected to feed cold water to both of these things. Initially we'll just be using the water for laundry. We want to bring uses on board one at a time out of an abundance of caution. To this end we purchased a simple pH test kit and before we connected up the pump and sediment filter, and ran a test on the water. Turns out its very much on the alkaline side of things, somewhere between 10 and 11. My questions are;

1. What would cause the alkalinity of the water? (My suspicion is there is left over baking soda in the tote and a thorough rinsing might solve the issue, but could it be something else?)
2. Is there a way to reduce the alkalinity and make the water more neutral?

As it stands at the moment I'm envisioning a point where I put a hosepipe on the washing machine cold water feed and just run the current supply outside then rinse and repeat until the pH returns to something more neutral. As I've said we have 2 totes so we can drain and flush one at a time or move all the water into a single tote if necessary. Thanks in advance for your advice.

Have you checked ph of rainwater separate from what is in the storage tank?

It does not sound alarming to me. I would not drain it considering it is only being used for laundry. I don't have the benefit of the rain you have though. It could be weeks for another rain. That plays a factor.

wayne fajkus wrote:Have you checked ph of rainwater separate from what is in the storage tank?

It does not sound alarming to me. I would not drain it considering it is only being used for laundry. I don't have the benefit of the rain you have though. It could be weeks for another rain. That plays a factor.

not yet, we're due more rain tomorrow so will catch and test some then.

Andy,

I suppose that if alkalinity were a problem you could add just a little vinegar and check the ph again.  Is alkaline water going to be a problem?  Rainwater is naturally slightly acidic, so if the problem is caused by baking soda, the problem may resolve itself over time.

Please, let me know your thoughts,

Eric

Eric Hanson wrote:Andy,

I suppose that if alkalinity were a problem you could add just a little vinegar and check the ph again.  Is alkaline water going to be a problem?  Rainwater is naturally slightly acidic, so if the problem is caused by baking soda, the problem may resolve itself over time.

Please, let me know your thoughts,

Eric

Hi Eric,

To be honest we're so new to this that I'm just trying to be very careful. I've read that drinking water should have a pH of no higher than 8. It's entirely possible that undissolved baking soda could be the issue and the more it gets diluted the lower the pH will get. It's also possible that the pH of the rain is high. I'll know more on that tomorrow when I catch some fresh rain and test it. I'm not even sure that running high pH water through the pump and sediment filter won't damage the equipment itself. Now I've seen the online fads about drinking alkaline water but even those only have a pH of 8 or 9, so we're currently way past that.

One thing I've learned is that for the first 49 1/2 years of my life I took running water and drinkable water very much for granted. Now that we're in a spot that is too small for a well and we're having to collect rainwater I'm really starting to appreciate the whole turn-on-the-tap-and-out-comes-the-water thing that "normal" people enjoy.

pH of rain should be below 7 normally 6.8 or so. Unless it is coming off a roof raising the pH, this is something else. Probably not baking soda as that is buffered at about 8 if I remember.

The reason is that there is a small amount of carbonic acid from Co2 that equilibrates in water lowering the pH.

What is it going through before the test chamber?

Is it passing cement at some point especially fresh cement?

Yes, sounds like baking soda residue, maybe a compounding of alkaline substances in the entire pipeline.

Wouldn't worry about it, your 'whites' should be the whitest in town for a while!

On another note, do you know the previous use of those IBC's? If not already aware, that's VERY important as they can have a long and varied life-cycle carrying all sorts of safe and extremely hazardous liquids. Ones that have a history of carrying things like wine, olive oil, etc are obviously okay, but, those with an unknown history should be avoided unless their use is not related to human, livestock or 'organic' garden practices.

Please be carefull and remember that pH of 10 is 1000 times more alkaline than neutral.

I just tested a 3% solution of baking soda dissolved in pure water with a lab grade pH meter, and got a reading of 8.3.
How accurate is your measuring system? Do you have anything to calibrate with that high? Also, you definitely used baking soda, not washing soda, correct?
If it were me, I’d check the rainwater, and rainwater with baking soda dissolved in it, see if you have anything close to the water you tested before. If rainwater and baking soda measure a lot lower, I’d start wondering what other residues might be in my equipment. I wouldn’t try to drink it, but by itself, pH 10-11 will just dry out your skin, it won’t burn. However, I might worry that whatever is increasing the pH is accompanied by some other chemicals, especially if my equipment was used.

Baking soda has a pH of 8.5 irregardless of its concentration (mostly). So that is not where the pH11 to pH10 is coming from. Maybe the strips are faulty. I would measure a range of different things and see if the result are off more than 1 from the expected range.

I have also heard of acid rain but never/rarely heard of alkaline rain. Do you have volcanoes near you? Even with the few know causes of alkaline rain, the pH was 8 or less vs the normal pH of 5.7 for regular rainwater. I am beginning to suspect that the IBC totes was previously used to shipped something with a high pH and the seller didn't realized or it was misidentified. In general its best to get used IBC tote that was used to ship food-grade syrup, oil, etc. Things that you can observe.

Mandy Launchbury-Rainey wrote:Please be carefull and remember that pH of 10 is 1000 times more alkaline than neutral.

Mandy is correct.  pH is a logarithmic scale.  Each change of 1 pH is either 10 times or 1/10 as acidic.

There are a number of things that can raise the pH.
Which one you want to use depends on what you are planning on using the water for.
If you are experienced at using chemicals and have the proper safety equipment, a small amount of muriatic acid can drop the pH in a hurry.
Glacial acetic is a little less effective, but, WAY less dangerous.  But, I'm thinking the acetic acid may be hard on plants.
Perrier will drop the pH if you want to spend crazy amounts of money.

Personally I recommend that you try testing strips from a different company. and if it still persist, empty out the IBC tote and try again. if it still persist and the high pH is caused by your roof. I would recommend moving. And if it is cause by the opposite of acid rain, I recommend leaving that county/state. At this point I am hoping it is faulty test strip or toxic mislabel IBC tote.

Maybe I should recheck my sources on this (Geoff Lawton videos and HS Chemistry 20yrs ago), but a ph of 11 correlates with metals like aluminum, which are very toxic to drink. Is your roof aluminum, or coated with some other highly alkaline metal? If so, I'd be very concerned about drinking it. I would also retest, and get another type of test done to triangulate for accuracy. I'd also test the rain straight, the runoff of the roof before the tote, as well as the water in the tote and out of the tap. This should give some clues. If it is your metal roof, I'd scrap that as your drinking water and run it through a bunch of woodchips or biochar and see if it comes through safe for irrigation. I don't see your region on your profile, but if you get more than 30" of rain and its relatively evenly distributed through the year, you could build another structure (wood shed, barn, etc) and put on a roof that is appropriate for drinking water catchment. That or replace your roof. This would be a bummer but heavy metals are the source of extreme alkalinity in my understanding and are nothing to be messing with in your drinking water. Best of luck.

Ben Zumeta wrote:run it through a bunch of woodchips or biochar and see if it comes through safe for irrigation.

Good advice there.
May or may not help, sure won't hurt.

Another source of extreme alkalinity I just remembered is chlorine.

Chlorine is a tricky one. Technically it (Cl2) has a pH of 7.5, but hydrochloric acid (HCl) has a pH of 1, thus very acidic. And bleach (NaOCl), which are are referring to is very alkaline with a pH of 11, technically it is caustic lye (NaOH) combine with neutral Cl2.

Any updates on this? I'm interested to see if the cause was determined.

Thanks

Not much in the way of an update yet but here's some additional information.

The roof is a brand new metal roof with a powder coated finish (I think, either way its coloured from the manufacturer).
The rainwater flows from the roof into white plastic eavestroughs, down white plastic downspouts and into rainbarrels that were previously used to ship maple syrup. Then it flows through black poly pipe into two 1000L IBC totes which were previously used in the dairy industry and are food grade. They were filled with 1000L of water each and a kilo of baking soda was stirred into each one. They were then left for a minimum of 24 hours and then emptied. They were kept out of the sun from the day we got them.

We have added a fitting to our plumbing that will allow us to connect a hosepipe to the water and transfer it all from one tote to the other. The plan is to hose down each tote in turn as well as the rain barrels to make sure there is no residual baking soda clinging to the insides of anything. Given the ambient temperature around here at the moment I suspect any residual baking soda is having an issue dissolving but continued rain collection and the rinsing previously described will help bring the pH down over time. We're not planning on doing much with the water for the time being beyond running the dishwasher and washing machine with it. Once the pH gets down to a more normal level we'll test it for consumption. Til then I'll post updates as I complete the steps mentioned above. Thanks everyone for all your input, its very much appreciated.

I’d test some water coming right off the metal roof, which would be my main concern regarding the cause of the alkalinity.

The solubility of Sodium Bicarbonate is 70g per L of water at 1C/38F, so 70kg per 1000L tote.
https://en.wikipedia.org/wiki/Sodium_bicarbonate

1L of water =1kg of water, so 1000kg of water can dissolve 70kg of sodium bicarbonate
I really don't see why your tote would have a problem dissolving the 1kg of sodium bicarbonate when it can dissolve 69kg at 0C, and 96kg at 20C.

The pH of baking soda is pH = (6.37+10.25)/2 = 8.31. So I don't see how it can account for you pH in the 10-11 range.
(The same wiki link above will show you the pH or just do a quick google search for pH of baking soda)

Personally I am very concerned about the unknown cause for the high pH. Its some other compound/metal, where is it coming from? Is it safe to add this unknown metal/heavy metal to my plates, pots, cup and then drink/eat from it.