By Jesse Savou, ARCSA A.P. and founder of BlueBarrelSystems.com
IMPORTANT NOTE: BlueBarrel specializes in rainwater catchment systems made from recycled (once-used) barrels. Ours is a non-potable water storage solution, intended for garden irrigation and other non-potable uses. While any water can become an emergency backup supply with proper treatment, BlueBarrel does not sell potable water storage or treatment solutions, and we do not endorse specific methods for treating stored water to safe drinking standards. This article contains informational content only and does not constitute professional advice.
While rainwater is virtually the cleanest water available; once it's rolled off your roof, through your gutters, and diverted into rain barrels, it is not considered safe for drinking because of the contact exposure along the way. This is why water testing is important, should you ever need to treat self-stored water for drinking as an emergency backup supply.
If you are storing rainwater at home, a small investment in personal-scale water treatment and testing options makes an important contribution to your emergency preparedness plan.
While emergency preparedness is a hot topic, rainwater can actually be a primary drinking water source if you work with the appropriate professionals to design a potable storage and treatment system. This is common practice in remote or island-based communities worldwide. In fact, recognizing the very high quality of rainwater and its great availability (given enough storage), rainwater as a primary drinking source is becoming more and more common in the western world.
Here's what we know from an avid rainwater harvester in Texas:
"Wells in our area have TDS [total dissolved solids] of 300 ppm up to over 1,200 ppm while our rainwater system runs 4 to 5 ppm TDS . Lot of wells in our area have iron and sulphur, which result in an odor . Some area wells also have a high concentration of fluoride. That’s why we wouldn’t trade our rainwater for anything else." - John K.
Rainwater for Emergency Preparedness
Emergency preparedness is one of the many benefits of collecting rainwater on site. While most people are primarily motivated by having a sustainable water source and high quality water for their garden, rainwater harvesters also acknowledge that having hundreds of gallons of water in storage offers tremendous peace of mind. This water can be treated in an emergency if the regular potable water source is compromised.
While boiling and chlorination can purify water, emergency preparedness experts recommend having more than one treatment method available. In an emergency, any one method may not be realistic. For example, you may not be able to operate your stove in a power out. In an earthquake, gas lines may break, and so might bleach bottles. When the initial quality of water is unknown, it is safest to use two treatment methods anyway, to take care of a wider variety of pathogens that may be present in the water.
And how will I know if my water is safe to drink? Test it!
Realizing it may not be possible to test treated water in an emergency situation, I decided to be proactive and test my stored rainwater just to see what’s in it.
I must say I was pleasantly surprised by the results.
I used the WaterSafe brand, who offers two versions of a user-friendly home water test: one for city water and another for well water.
Both versions test for bacteria, pH, hardness, nitrates/nitrites, chlorine, pesticides, and lead. The well version includes an iron and copper test in addition to the others listed above.
Either version can be used for rainwater. My recommendation is to use the well water test first, because it tests for more elements.
If your iron/copper test comes out negative, you can use the city version for future tests. Some roofing materials do contain iron and copper, so it’s worth testing for these elements at least once.
For my initial test I used both versions of the test. I wanted to test for iron and copper in my first go-round. I also wanted to see if there was any discrepancy in the common factors.
All of the tests were very easy to run with a small sample of water, and all special equipment was provided. Apart from the bacteria test, which needs to sit for 48 hours before giving a reliable result, all tests could be completed in a matter of minutes.
I tested rainwater that had been in storage for about six months.
I was not surprised by most of the results. Rainwater is known to be very high quality water, with an ideal pH factor for plants. Here's what I found:
Water Testing Results by Factor
The pH read between 6.5 – 7.5. This is ideal drinking water range, and also much better for plants than city water which is treated to be alkaline.
Total Hardness (Hd)
As rainwater is 100% soft when it falls, I was not surprised that my water tested zero total hardness (ideal both for drinking and for irrigation).
Not surprisingly, chlorine yielded zero. While chlorine is a common additive to any controlled water source, rainwater is completely free of chemicals - again, ideal for drinking and for plants.
Nitrites measured zero, while total Nitrate/Nitrite read between 0.5 and 2.0, well below the threshold of 10.0 for safe drinking. Nitrates are very good for plants so while this low reading is good for drinking water, it's nice to see the potential for at least a little nitrate delivery in my irrigation water.
Lead (Pb) and Pesticides
The lead reading was zero. I would only expect lead if it were in my roofing materials. These days most building materials do not contain lead, but as we know from Flint, MI; it’s important to test for lead when testing drinking water.
I believe the pesticide reading was negative (the left line is certainly darker than the right), but this reading was a little less clear than the others. (What do you think?). I do live on a farm property, and although we do not use pesticides here, it’s possible that our neighbors do, so it’s not completely out of the question that there may be some pesticide residue on our roof.
Copper (Cu) and Iron (Fe)
Copper and iron also yielded zero. Based on this result I will use the city water test in the future.
Bacteria (E. Coli)
The test that really surprised me was the bacteria test. This test consisted of a white powder and a small vial. I poured the powder into the vial, and then filled with rainwater to the fill line. I shook for the specified amount of time and then waited 48 hours to read the results. Purple means negative for bacteria, yellow means positive. While rain is totally clean as it falls, it does roll over the rooftop on the way into the rain tanks, picking up pollen, tannins, and any other boogies that may be on the roof or in the gutters. I was expecting to see yellow pretty quickly. When my shaken sample was purple, I thought certainly after 2 days’ time the sample would turn yellow. To my shock and amazement, both tests confirmed the same result – that my sample was negative for coliform bacteria.
Upon further investigation, I learned that drinking water tests focus on coliform bacteria, because these are an indicator for a wide range of harmful bacteria that may be present in drinking water. Other types of bacteria are not considered harmful, so they are not regularly tested for.
Total Dissolved Solids (TDS)
TDS was not part of this test kit, but I have an inexpensive TDS meter that also takes quick temperature readings - very nifty! The TDS reading for my rainwater was 30. Compare that to 10 for bottled water, and a whopping 230 for our well water.
Apart from the inconclusive result for pesticide, these tests prove what is known worldwide, that rain is our highest quality water source. The results also suggest that my rainwater is perfectly safe for drinking, even after 6 months in storage. That said, I will certainly treat this water if I ever choose to drink it. I do suspect my water contains plenty of bacteria, even if the tests proved that it does not contain harmful coliform bacteria, and the water quality may change over time.
I can say, though, that based on these test results, I will drink this water quite confidently after basic treatment, should I ever need to.
Have you tested your rainwater? Contact us to tell us about your results!