Why do you need to purify water?

Wherever you get your water it may need purifying. I’ve researched all the reasons why filtering and purification are necessary before you use it.

Water from most sources requires purification to make it safe to drink. Most well water contains contaminants from the environment and human-made pollutants. Rain collected from your roof can pick up dirt and bacteria after it falls. Even city water could contain heavy metals and high concentrations of minerals.

The quality of water and the contaminants it may contain depends on where you got it from and what you want to use it for.

Related reading: 8 ways to purify water for your off-grid home.

Check out my recommendations for the best water supply and plumbing equipment.

Where do you get your water?

Water from different sources is likely to be contaminated in different ways.

City water

Researchers have found a surprising number of contaminants in most city supplied tap water. Although water utilities thoroughly treat it before pumping it out to houses, some pollutants remain, but it picks up more as it travels through pipes and pumping stations.

The Environmental Working Group (EWG) have conducted several long term investigations into tap water quality and have found that the extent of its contamination is considerably under-reported. The number of harmful chemicals and substances that could make their way into your water has increased in the last few decades, but the list of regulated substances remains the same. Consequently, many of the contaminants remain in the water legally.

Well or spring water

Underground water sources can suffer moderate to heavy contamination from metals and minerals. Also, human-made chemicals, byproducts, and bacteria can leak into them through the soil. In most cases, the levels are low enough not to be immediately harmful, but longer-term use could cause them to build up in your body systems. 


Despite having just passed through a form of distillation, rainwater can still carry contaminants. As it passes through the air, it is likely to remain pure and safe to drink; however, as soon as it hits the ground or a collection surface, it can become contaminated and requires purification.

All rainwater collection surfaces, particularly rooves, must be left open to the elements. This means that leaves, dirt, and even microbiological organisms can build up on it, only to be washed into your collection system.

Products like the first flush diverter allow you to discard the most contaminated water, but they don’t prevent the rest of the water from being contaminated. Despite this, rainwater is an incredible source of water and is likely to be the easiest to get to a drinkable standard.

My article calledHow to get an off-grid water supply without a well goes into more detail about rainwater harvesting, including first flush diverters.

How are you using the water?

How you intend to use the water you’ve collected or pumped in, will often dictate how you must treat it.

Non-potable systems

Non-potable systems include garden irrigation, toilet flushing, and even some cleaning applications. Water from most sources can be used for most of these with basic filtering. As non-potable water is not for consumption, the risk posed by any contamination is considerably less.

However, many people prefer to put all water, including that destined for non-potable uses, through a series of filters. This is often to remove any large particles that may cause residue, staining, or off-putting odors.

Potable systems

For potable systems, both filtering and purification should be carried out to remove metals, minerals, pesticides, bacteria, and viruses. To produce safe drinking water, it should be subjected to a several stage process designed to filter out any particles and kill any microorganisms.

Often water entering a house is treated with a whole house filtration system. Then potable water can receive further treatment from additional systems like reverse osmosis or UV purification. These units are often located directly under the kitchen sink or under the floorboards close to any drinking water taps.

Walmart stock some excellent reverse osmosis systems, like the 5-stage unit from Yescom, for around $100.

Possible contaminants

Contamination can occur anywhere from the water source until it reaches your filtration system.


Bacteria such as e-coli are commonly found in water sources. They are present in decaying bodies and fecal matter in the ground. From there, they can spread into groundwater and end up in your well.


Viruses can be found in some water sources and cause a range of illnesses. Symptoms can take several weeks to occur, but in most cases, you will experience severe diarrhea and vomiting.


The most common waterborne parasites are protozoa called Giardia and Cryptosporidium. Both enter the water source via the feces of humans and animals, and Giardia contaminates most bodies of water in the US. Cryptosporidium has a three-day incubation period, and both can cause severe gastrointestinal symptoms and can be severely harmful to your health.

Toxic metals

Metals like arsenic, barium, chromium, lead, and mercury can be present in some water from a broad range of sources. Some come from the natural environment, but others come from industrial waste, pollutants, fertilizers, and road runoff. Many of these can build up in your system and cause severe conditions.


Herbicides, insecticides, and fungicides used in fields often wash into waterways or leach through the soil into groundwater. They can become concentrated in the water but remain at relatively low levels. As with toxic metals, the danger occurs if they build up in people’s bodies over time and cause chronic conditions. Research indicates that these could include cancer, Alzheimer’s Disease, ADHD, and even congenital disabilities.

Radioactive elements

Radioactive elements can be present in water because of contamination from human-made sources, but most come from naturally occurring substances like uranium. This is present In the ground and can find its way into the water.


Hardwater is water that contains significant levels of minerals; it is known to produce scale and build up in pipes and faucets. The presence of these minerals is more of a nuisance than a danger. They can include substances like potassium and sodium, which are both known to build up and leave patches and residue.

It’s not necessary to remove all minerals, and mineral water is often mentioned as providing small amounts of some beneficial substances. Still, it is often necessary to control the levels found in your supply.


Wherever you source your water, purification is a necessary step to ensure it’s safe and healthy for you and your family. If you want to use it for flushing your toilets or watering your garden, you may like to use minimal filtration, but for washing or drinking as many contaminants as possible should be killed or removed. To best understand how you must treat your water, you can first test it water (check out the price of this 14 in 1 testing kit on eBay) to see how it is contaminated.

Check out my recommendations for equipment that will help you take your home off-grid.

My Off-Grid Product Recommendations

Useful Book: Off Grid Living 2022-2021 – This incredible step by step guide is a great read and gives you useful information about reaching self-sufficiency in just 30 days. Get the paperback on Amazon or read it free with a Kindle Unlimited subscription or listen to the audio version with Audible Plus membership.

Small Solar Panel Systems: Silicon Solar – This is an excellent company that offers lots of products to get you started on your solar journey. Visit Silicon Solar.

Family Water Filter: Big Berkey – For a fast, affordable water filter with no plumbing required, you can’t beat a Big Berkey gravity-fed filter like this one from Amazon.

Canning Equipment – This canning starter kit, 22-quart Barton pressure canner and twelve-pack of Ball 16oz mason jars will help you preserve food as you work towards self-sufficiency.

Cleaning: Fuller Carpet Sweeper –. This carpet sweeper is an ideal way to keep your home clean without using up your energy stores on vacuuming.

Handy Knife: Gerber Serrated Paraframe – This handy all-purpose knife is lightweight and ideal for all those little jobs around your home and garden.

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