Pool water in a post-crunch scenario

It’s been a quiet morning at work, so I made some brief notes about the potential use of residential swimming pools as a post-crunch water source. I hope to add to this over time.



Firstly, to summarise – don’t use pool water unless properly treated first. We just don’t know what’s in it.



Secondly, warnings:



NEVER, EVER DRINK OR USE POOL WATER UNLESS PROPERLY TREATED FIRST.



NEVER ASSUME POOL CHEMICALS ARE OF FOOD GRADE – for example, sodium bicarbonate used in pools is not a suitable substitute for culinary sodium bicarbonate.



NEVER, EVER MIX CHEMICALS - EVEN OF THE SAME TYPE – AS SOME WILL REACT EXPLOSIVELY.



NORMAL RULES FOR STORAGE OF CHEMICALS APPLY.



DON’T ACT ON INFORMATION PROVIDED HERE UNLESS YOU’VE VERIFIED IT YOURSELF. I’M NEITHER A CHEMIST NOR A DOCTOR.



Given the number of residential swimming pools in Australia, it makes sense to consider their worth as a water source post-crunch. Due to contaminants that may be present in the water, an understanding of pool maintenance may help if things go south – both in terms of using the water, repurposing pool equipment, and using pool chemicals in a variety of ways.



Pool water is treated in two ways: Filtration - as every prepper knows - is the removal of particles from the water, and chemistry – in a pool sense - involves providing an environment that is inhospitable to microorganisms yet safe for human immersion.
It is never intended to be safe for human consumption.


I hope to look at filtration and other pool equipment another time.



Let’s start with water:



There are three ways contaminants can enter pool water: with the original water used to fill/top up the pool, contaminants added intentionally, and contaminants added accidentally.



Original water quality - Pools are most commonly filled from any combination of the following sources: scheme (ie tap) water, bore (ie ground) water, rainwater, and/or surface water (ie ocean, river, lake, etc). Water that is delivered to the pool in a truck or fire hydrant water may originally be sourced from any of these. Rural pools are occasionally filled with dam water. Obviously we don’t know what contaminants may be in any of these sources.



Intentionally added contaminants – Typically in the form of pool chemicals. Again, we never know exactly what has been added to the pool over its life, even if we see chemical containers at the pool. There are many “specialty” chemicals that may be extremely toxic if consumed. Others may cause skin irritation or poisoning via absorption through the skin. I’ll cover this in more detail below.



Accidentally added contaminants – bird droppings, organic matter and dirt being blown into the pool, overspray from roof resurfacing or fence painting, rubbish being thrown over the fence by a grumpy neighbour, etc. There’s no limit to the number of ways that contaminants can enter an open body of water. Furthermore, if the pool is not being maintained it will turn quickly – it may not be possible to see any objects (ie dead animals) under water.



In short, pool water should never be used for drinking unless suitably treated first (ie reverse osmosis, distillation, etc). Even high-end water filters and boiling won’t remove some toxins and minerals (eg dissolved salts) from pool water. Even using some pool water for washing, etc, may be dangerous.



POOL CHEMICALS



As mentioned above, pool chemicals are based around providing an environment that is inhospitable to microorganisms yet safe for human immersion. Durability of the pool and equipment materials is also a consideration. Sanitising the water is the basis around which all other chemical issues are based. Other chemicals provide an environment in which sanitisers will work.



Here is the list of sanitisers as shown in AS3633 – the Australian Standard for domestic pool water maintenance:







Here are some notes I’ve made:



- Chlorines – I cannot stress enough, NEVER, EVER MIX CHEMICALS - EVEN OF THE SAME TYPE – AS SOME WILL REACT EXPLOSIVELY. This even extends to avoiding re-using a container for chemicals, even if they’re the same brand & type. I have seen explosions that you wouldn’t believe from this.

- Calcium hypochlorite is most commonly bought as 65-70% granular chlorine. I don’t like the tablets as they’re not as convenient for use. I store this granular pool chlorine instead of liquid bleach for household use as it lasts so much longer. This can also be used for treatment of drinking water.

- Sodium hypochlorite – the same active constituent as household bleach. Short shelf life is a problem.

- I’ve never seen or used Lithium hypochlorite. I know precisely nothing about it.

- Sodium dichloroisocyanurate and Trichloroisocyanuric acid are forms of chlorine which include a UV stabiliser. Do not ever drink water that has had these added.

- Electrolytic chlorine generator (Salt chlorinator) - the most common sanitiser system in Australian domestic pools. Salt water is passed through an electrolytic cell, causing the chlorine ions in the salt to form chlorine gas bubbles. Some systems use NaCl, some use other mineral salts, none of which are suitable for consumption.

- Sodium hypobromite – rare. I recommend avoiding consumption of any pool water containing bromine-based pool chemicals.

- Bromine – commonly used in spas but rarely in pools, as it is more stable than chlorine in high water temperatures (up to around 40 C) but much more expensive. Some pool owners use this when chlorine-sensitive skin is a concern.

- Polyhexamethylene giuanide system – Rare, but becoming more common following an automatic injection system hitting the market. DO NOT mix with any form of chlorine, including saltwater pools as it reacts to form a pink, jelly-like sludge.

- Hydrogen peroxide system – likely to become more common following an automatic injection system hitting the market. This is an interesting one – I’ve seen goldfish swimming happily in water treated with this system, so it will be worth looking into from a prepping perspective.

- Ozone generator – requires a residual sanitiser, but ozone will kill microorganisms around 3,000 times faster than chlorine. I’m hoping to connect one to a water tank to take out anything living in the drinking water - this has been done many times with success.
- Chlorine gas – only used in commercial pools. Extremely dangerous; do not handle without proper training. Can be fatally toxic (chlorine gas was often used in gas chambers)
- Bromine liquid – rare, although can be used in certain automated injection systems.

- Iodine – rare.

- Ionic water sanitiser – uses copper and silver ions to kill microorganisms, in the same way that ancient Romans put a coin into drinking water to stop it fouling. Not good for pools, but may be worth looking at for its post-crunch uses.

- Magnetic water treatment – Rare. I’ve never seen any reference to this, other than AS3633 saying it isn’t recommended. That said, it may be worth looking into for other preparedness related uses.


That’s the sanitiser side of things. However, for the sanitiser to work, other chemicals must be in balance. Most notably:



- Total Alkalinity (“TA”) – a measure of carbonates and bicarbonates in the water. If too low, pH will be unstable. Raised by using sodium bicarbonate (which has a myriad of other uses).

- pH – a measure of how acid/alkaline the water is. Raised using various alkaline chemicals, lowered with various forms of acid. These too can be useful for the prepper.

- Stabiliser – usually cyanurate-based, these protect chlorine from UV attack. Very toxic.

- Algaecides – often copper-based, these are used to kill algae if the regular sanitiser isn’t doing the job. Toxic.

- Pool Salt – yes, it’s regular salt. Just remember that it hasn’t been cleaned as thoroughly as salt intended for consumption. When added to pool water it will leave a brownish scum on the surface until filtered out.

- Specialty chemicals – decades ago, pools almost exclusively used granular chlorine, so pool shops (and chemical suppliers) sold it literally by the truckload. Since saltwater chlorinators became popular, chlorine sales plummeted, so new chemicals had to be made to keep sales high. Many of these serve no particular purpose, some cause more problems than they solve. Assume all to be toxic unless otherwise known as fact. One major concern for the prepper is that some of these may have been added to a pool and we’ll never know.


The verdict on post-crunch use of pool water? Don’t use it – even for washing - unless you’re able to remove a variety of chemicals, toxins, organisms and other contaminants from the water. It may be possible to use some pool water types for watering plants, but I’d recommend against it unless you know precisely what’s in the water.



I’m hoping someone with more knowledge of distillation techniques can share the best ways to distil pool water; if possible, this can potentially lead to reservoirs of tens-of-thousands of litres of water when it may count the most.