In the series of previous articles, we addressed the issues related to potential sources of water at off-grid locations:
It’s an old idea, that thanks to modern implementation may provide a reliable source of water for off-grid households, particularly in wet climate zones.
Source: Basic elements of the Rainwater Harvesting System (in red Pre-Filtering system). Source: Your Home (Australia’s guide to environmentally sustainable homes)
See: à Rainwater Harvesting (series of articles)
Deep underground water
Source: Environment Canada / USGS
Streams, lakes… etc… are prone to chemical and biological contamination. They collect runoff water from city streets, industrial areas as well as from the agricultural and livestock industry. The runoff water is not only carrying particles of dust, sand, etc… (“muddy” water), but also tons of chemical toxins and a whole spectrum of more or less deadly microorganisms. Note, that big rivers and lakes may substantially dilute the effect of contamination from usually local runoff waters, but small creeks and streams will be overwhelmed by runoff contamination, and it may take days to bring them back to the “safe” state, ready for processing by individual, household-type purification systems.
Note that small, stagnant water sources are especially dangerous from this point of view. While Mother Nature usually takes care of dead organic matter (although it may take time), some microorganisms may thrive in such an environment and the concentration of chemical toxins will rather increase with time.
They are less prone to contamination because layers of ground act as natural filters for runoff waters. In this sense, they can be considered as Low-cost “gifts” from Mather Nature.
Source: A little spring in Tyrol (openstreetmap.org)
Commercial delivery (Water Hauling)
It’s probably the most reliable source of drinking-quality water at off-grid locations. It requires local storage tank(s) and is characterized by “relatively” constant (fixed) cost on a “pay-as-you-go” basis.
Unconventional sources of water
Systems based on “Fog Catchers” – relatively inexpensive, passive (no need for energy), and safe. However, practical only in specific areas with enough moisture in the air.
All these freshwater sources can provide water with quality usually largely exceeding most of the household’s needs – namely:
a. Toilets, irrigation of ornamental gardens
(typically requires water w/no sizable debris)
b. Washing machines
(Laundry and Dishwashers may have limits for the level of chemical and bacterial contamination, some dangers can be eliminated by using suitable disinfectants:
– for laundry chorine-based bleach, hydrogen peroxide, sanitizers (popular Lysol)….
– for dishes, these must be disinfectants approved for use on “food-contact surfaces” (typically calcium and sodium hypo-chlorites, peroxides, etc…)
Note: There is a difference between Sanitizers and Disinfectants. Sanitizers kill bacteria but do not harm viruses. Disinfectants do the full (100%) job of killing bacteria and viruses.
Soaker hoses as an example of subsurface irrigation. Source: “How to Install Soaker Hoses in Your Vegetable Garden” by
by Shelley Stonebrook, (Grow Veg)
Partially, the contamination can be removed by washing veggies and fruits in warm water as well as peeling fruits (whenever possible). The best solution however is to use the “Subsurface” Watering System as it will lower (or even eliminate) exposure of green-leave veggies and surface-grown fruits to contamination.
Usually more stringent limits due to the possibility of swallowing the shower water or exposed open wounds.
e. Washing hands
Most soaps (solid and liquid) include antiseptic components acting as sanitizers or disinfectants
So basically, the only exception is the potable water
For well-understood reasons, Drinking Water has very strict limits for bacterial and chemical contamination.
Typically, only deep-water sources and Hauled Water can meet potability requirements. Water from any other sources will need extra Filtering and Purification (Treatment) systems to make it safe for consumption.
Note: It is widely accepted that boiled water is bacteriologically safe for drinking because at 100 oC (212 oF) all living organic matter (pathogens, bacteria, viruses, etc) is killed. It should be noted, however, that the boiling process does NOT remove chemical contaminations (toxins), so not all boiled water is safe for drinking!
Source: “How much water should you drink?” by Harvard Health Publishing (Harvard Medical School)
The level of chemical and bacterial contamination of shallow underground water and surface waters (lakes, streams, and possibly springs) must be taken on a case-by-case basis. For example, in areas of intensive agricultural activity water will be exposed to chemicals like fertilizers, weed & insects’ killers (herbicides, pesticides). In industrial areas, contamination will also include numerous (usually toxic) heavy metals as well as chemical components from industrial gases. And finally, in an area with livestock operations, the water will be contaminated by animal waste (a plethora of microorganisms instigating often life-threatening diseases) as well as pharmaceuticals.
The bottom line, for safety, drinking water must undergo three levels of treatment:
Pre-filtering should remove all visible debris and contaminations like leaves, dead insects, but also sediments carried by runoff water. This is the simplest stage of filtering. It’s not excessively expensive as the filters do not have to meet some specific government-issued requirements. Rainy periods will put more stress on the pre-filtering system (more frequent cleaning and eventually replacement). The effectiveness of pre-filtering can be easily assessed by visual inspection (no debris, change of muddy water to much clearer one, etc….
2. Fine Filtering (Purification)
iSpring WGB22B-PB 2-stage whole-hose water filtration system w/ Carbon block and Lead reducing filters
Purification Water Filters are designed for the removal of minuscule particles as well as soluble chemical compounds, toxins, odors, heavy metals, minerals (including calcium, magnesium), pharmaceuticals, etc. To some extent, filtering can also reduce the number of larger microorganisms. However, this type of purification process does not eliminate bacteria, viruses and in general – pathogens, so while it is the necessary part of the Water Treatment process in off-grid locations, it is not guaranteeing water’s potability. Note, that Water Purification Systems are often used in individual households connected to municipal water, just to remove calcium, chlorine, and other minerals and chemical elements that may exceed your level of tolerance. However, it is assumed, that municipal water is free from microorganisms, so you do not have to take care of them.
These types of purification filters are more complex and costly than standard mechanical pre-filters. Usually, they require periodic replacement, and their effectiveness cannot be easily assessed because most of the chemical components are soluble, so invisible to the naked eye. That’s why their use must follow guidelines (maintenance and replacement) defined by manufacturers. And in specific cases (like higher than “typical” level of contamination of the water source), you may have to replace filters even more frequently
Warning: These kinds of Water Filters not only do not eliminate bacteria and viruses. When left unused with standing water (typical examples are weekend houses), they can act as “breeding grounds” for the multiplication of microorganisms.
a. Traditional disinfection method
This stage of the Water Treatment System makes the filtered water also a drinkable one.
It is not based on the filtering process but rather on creating deadly (but unharmful for humans) conditions for microorganisms. On the commercial (municipal) scale, the most popular method is chlorination, however, it is not a fully safe solution for individual off-grid households, because the chlorine is not benign for humans (or at least it is not “pleasant” due to the taste and odor of chlorinated water). The level of chlorine must be strictly controlled, because too little means surviving pathogens, and too much means potentially harmful consequences for humans.
VIQUA – VH150 UV Disinfection Unit for the whole home
b. Novel methods of water disinfection
That’s why practical solutions for individual households are rather based on UV radiations and/or ozonation (those having Jacuzzis may already know this trend). Unfortunately, unlike chlorine-based systems, UV or Ozon-based systems require electrical energy, which may be challenging at off-grid locations.
Note, that most Disinfecting Systems do not remove particles, chemical compounds, non-organic contaminants including toxins. As the matter of fact, they also do not remove microorganisms, however, they destroy (kill) them, so they are not any more harmful for humans.
Another, although the more costly method of Water Treatment can be achieved by Distillation. It’s a one-stage process where the water is vaporized and then condensed back to the liquid form. High temperature kills microorganisms while the vaporization separates contaminants (including dead microorganisms) from the vapor, and then the vapor condensates back to the liquid form.
In recent years, more and more often such systems are used for water-desalination. Given the same physical “mechanisms”, the desalinated water is also disinfected.
On the commercial scale, such systems are implemented by using the set of (potentially sun-tracking) mirrors concentrating the energy of solar radiation and then focusing it on the “water tank”.
Concept of solar distillation system. Source: “Solar Desalination Using Fresnel Lens as Concentrated Solar Power Device: An Experimental Study in Tropical Climate”, (Frontiersin.org)
In hot climate zones, the use of such systems for obtaining potable water for the needs of an individual household may be justified.
Note: In contrast to a 2-stage system of Filtering and Disinfection, Distillation is a 1-stage process that removes all contaminants and microorganisms from the “treated” water. What you get is pure H2O, which practically is not possible to achieve in conventional Filtration and Disinfection Water Treatment Systems.
Water Treatment Systems for Drinking Water
In the US, the maximum allowed level of water contamination (quantity of individual contaminants and their profile) is regulated by the Environmental Protection Agency (EPA), based on the Safe Drinking Water Act. That’s why the starting point to make any decision about the individual Water Treatment System is to know the “quality” of your original water source. For that purpose, you will have to hire Government (EPA) Authorized specialist to perform adequate tests determining:
a) level of chemical and biological contamination in the given source of water
b. probability of sudden changes of the level of contamination due to impact of the local environment (runoff waters from areas of nearby agricultural & livestock activity, industry, and big agglomerations).
Source: Water or Killer – Drinking water contamination” by Afsah Kanwal, (Medium.com)
From this point of view, the type of water source plays big importance.
For example, deep-underground water sources most likely will have a small and rather constant (predictable) level of contamination, because deep layers of soil (earth) make a good natural filter. In other words, once the contaminants and their concentrations are known, you (specialist) can design the Water Treatment System that will guarantee the safety of drinking water over the years.
In contrast, surface waters (streams, creeks, lakes) are prone to fast changes in the concentration and composition of contaminants due to runoff waters.
When it comes to rainwater – its level of contamination will depend on the length of periods between the rain and the length of the rain itself as well as of the local air pollution. Longest the period between consecutive rainy periods means more contaminants will be collected by the catchment area. Intensive rain may quite well clean the roof, so First-Flush system(s) can efficiently divert the dirty water from the water collecting tanks. In contrast, drizzling rain will need more time to do the same job, so most likely First-Flush diverters may not be that efficient (either not all dirty water will be diverted, or all water (including clean one) will be diverted from the tanks).
See: Rainwater Harvesting: Pre-Filters
Typical contaminants of water sources
Out of thousands of possible water contaminants, the following are recognized by EPA as the most harmful and at the same time the most common (widespread) in nature:
1. Microorganisms (bacteria, viruses, pathogens, …
Life on Earth first evolved in waters, so no wonder that water is still a favorite place for microorganisms of which some are friendly, but many are harmful, and even deadly (E. Coli, Legionella, Salmonella, Giardia Lamblia, Cryptosporidium parvum, etc..)
Water Pollution – Source: Apec Water (freedrinkingwater.com)
2. Heavy metals
For long Lead (gasoline, paints, old plumbing…) and Mercury (thermometers, fluorescent lights, streetlights, …) were the main water contaminants. Now, the use of these metals is mostly phased out (although mercury is still used in the mining industry). Unfortunately, the damage to the environment was already done so these contaminants will stay with us for quite some time ….
Aluminum is omnipresent in Earth’s crust (it’s the 3rd most common metal), so naturally it is also present in the water. Note, however, that due to its widespread use by industry (including the food industry), the level of aluminum contamination is on the rise.
Arsenic and Chromium are rather local contaminants in areas of natural deposits and relevant industry.
Cadmium pollution is on the rise – especially in areas of smelters as well as municipal waste incinerators (plastic, nickel-cadmium batteries…)
Copper – Normally the level of copper in natural water sources is well below the limits of harmfulness (excluding areas of copper mining and processing). However, since most of the homes’ plumbing systems are made from copper pipes, the metal can “leak” into the water. Under normal circumstances, its concentration will be insignificant, however, if the water has been left standing in pipes for a longer period (seasonal houses), it is wise to run “first flush” (about 30 seconds) to get rid of potentially contaminated water.
Unfortunately, most of these metals are highly soluble in the water and so easily absorbed by the human body. They are classified as harmful to human health.
It’s a natural mineral, usually considered beneficial for tooth protection (that’s why it is commonly added to municipal water). Unfortunately, in “higher” concentrations, fluoride is detrimental to our bones (significantly weakens the skeletal system)
4. Chemical Compounds
– Organic substances (pesticides, herbicides, petroleum and its derivatives, detergents, cleaners, phenols, pharmaceuticals, dyes, humic substances, ….
– Inorganic substances: Nitrates (NO3) and Nitrites (NO2) – both found in fertilizers, but also manures and septic waste, they are the most common water contaminants in rural areas.
Also, to this class of contaminants belongs general chemical waste including plastics, ammonia….
Just for clarification: Organic substances contain bonded atoms of Carbone and Hydrogen (C-H), while inorganic ones do not.
The most common radioactive substances in drinking water are radium, radon, and uranium. In nature, they exist in very small concentrations, so normally, they do not cause any health problems. However, near nuclear plants, or places where nuclear waste is stored, their concentration may rise to dangerous levels. Another hidden radioactive danger is the result of
recently observed deployment of Depleted Uranium bombs (in this case the radioactive material is spread over vast areas of land, water, and air).
6. Newest Sources of Environmental Pollution
The mining industry in its intensive search for minerals (particularly so-called rare ones) as well as natural gas and oils (fracking technologies) makes use of huge quantities of unspecified chemical compounds and water that are pumped under the pressure into the ground. They cause severe contamination of deep-water sources and aquifers at an unprecedented scale. Similarly, the process of extracting oil from bitumen generates a lot of dirty water. Like it was in the case of the Tobacco industry, the content of “chemical cocktails” massively used by the corresponding industry is fogged by closely protected secrets. So be aware of the danger in areas of mining operations (extraction, processing, enrichment, etc…).
The possible impact of the fracking process on contamination of the deep-water sources – “Fracking the Planet” (Friends of the Earth)
Home Treatment Systems for Drinking Water
The type of Water Treatment System for an individual household is determined by the type of the water source (deep groundwater, shallow surface water, rainwater…) and its quality (based on tests run by an authorized specialist(s)).
Most of the sources (particularly shallow and surface water as well as rainwater) will require Sediment Filter(s) followed by the main Water Treatment Systems (Filtration and Disinfection). Provided the low mineral content (calcium….), most deep-water sources will require only the Disinfection Stage (although in justified cases even this stage can be eliminated).
While the complexity of the household’s plumbing system will be reduced if all of the water is treated the same way, practically, the potable water is required only for drinking, and some “toiletry” like tooth’s washing, skincare, etc (and potentially – dishwashing). By splitting the water systems for potable and non-potable, the size (and cost) of the Water Treatment System can be greatly reduced, while its lifespan increased.
Note that the properly functioning Water Treatment System is crucial for your health (and possibly life). Given the fact, that a continuous (automatic) control process of the quality of the drinking water is too costly to be implemented at the household level, you must make sure that:
a.The system is designed to meet the challenges of your water source
b. It is reliable (except pre-filters, DIY Water Purification systems are too risky given the possible impact on health)
c. Manufacturer’s specified maintenance is respected (including replacement of components)
d. Water’s samples are periodically tested (especially when you detect an unusual taste and/or smell of the treated water)
e. You closely monitor rapid changes in the quality of the water source due to natural “events” (flooding, seasonal agricultural works, the occasional intervention of government agencies against insects (spraying chemicals against mosquitos or trees destroying insects… ). Note, that your water treatment system may not be able to handle the temporary change of the contamination profile and rise of its level!
Source: Common Contaminants Found in Well Water, Extension, Alabama A&M & Auburn Universities (aces.edu)
Next page: à Active Carbon Filters (work in progress)