Gravity Water Filters & Home Water Treatment

Gravity water filters were designed to provide a water filtration solution for situations when – for various reasons – municipal water is not available. In theory, these filters can be used with all sources of water that haven’t gone through the municipal water treatment process (e.g. springs, rivers, lakes, etc.).

This makes gravity water filters extremely proficient at dealing with microbiological contamination issues, and water pollutants commonly found in untreated natural water sources.

But what if you wanted to use a gravity water filter for home water treatment? Would a gravity-fed filter be a suitable choice?

Features of Gravity Water Filters

Gravity filters are simple units capable of complex filtration. Here’s why you should consider a gravity-fed water filter:

  • Portability: Whether you’re going off-grid or planning to spend more time in your vacation home, gravity water filters have the advantage of portability. These systems operate independently of any water pressure or electricity;
  • Ease of Use: All gravity filters operate the same way — unfiltered water goes into the top chamber, which houses the filter candle, and ends up in the lower chamber filtered and ready to drink;
  • Complex Filtration: Despite their simplicity, these portable filters are veritable filtration powerhouses that are capable of removing numerous health-related and non-health related water contaminants from virtually any water source;
  • Mix of Filter Media: To achieve such high levels of filtration, the filter elements in a gravity-fed water filter combine ceramic filter media with activated carbon media;
  • Cleanable filter elements: Most ceramic filter candles can be washed under running water. This will extend their service life.

Given that these stand-alone filters are capable of removing even the most dangerous water contaminants, they’re used even by emergency relief organizations in case of natural disasters, in war zones, etc.

It is clear that these filters are the best choice in emergencies, hiking trips, expeditions, etc., but what about their efficiency in home water filtration?


Can Gravity Water Filters Be Used for Home Water Treatment?

If they can transform untreated water sourced from a river into potable water, gravity filters can certainly handle the purification of municipal water. Therefore, you can use them as a countertop water filter in your home or vacation home.

However, don’t expect the same performance from gravity filters as you would from a plumbed-in water filter system. Gravity filters have some limitations that may not make them the best choice in home water treatment


Limitations of Gravity Water Filters


Gravity water filters have two important limitations: Slow filtration and low filtered water output/hour.

Since they don’t work with water pressure and rely instead on the force of gravity to filter water, the process of filtering water with a gravity water filter is not instant.

It takes some time for the water to pass through the ceramic filter candles. For example, the Big Berkey (8.5 L) Portable Gravity Water Filter System delivers around 13 litres of filtered water per hour. Contrast this with the BMB Nano Ultrafiltration (UF) Water Filter System, which produces 180 litres of filtered water per hour, and you’ll understand the difference in filtered water output.

If your filtered water demands are higher than the filtered water output of a gravity water filter, we recommend using a plumbed-in undersink water filter instead.


Can Gravity Water Filters Tackle Municipal Water Contaminants?


Portable gravity filters can remove viruses, pathogenic bacteria, cysts, industrial and agricultural pollutants (herbicides, pesticides, solvents, heavy metals, volatile organic compounds), but also chlorine and THMs, making these filters a suitable choice for filtering tap water.

The only caveat is that not all gravity water filters will remove fluoride. So, if fluoride is a concern for you, you should check the capabilities of your system to see if it can remove fluoride as well. Some filters like the Big Berkey need additional filter elements to also remove fluoride, while other gravity filters like the Propur™ Traveller SS Gravity Filter System removes fluoride without needing extra filter elements.


How to Take Care Of Your Gravity Water Filter?

Gravity-fed water purification systems are much easier to care for than plumbed-in filter systems. They’re also easier to assemble and to replace their filters. However, there a few gravity water filter maintenance tips you should know of:

  • Some filter elements need priming before the first use: When you buy the filter elements air might be trapped within the tiny pores of these filter elements, so priming these elements can help force the air out of the pores and let water pass through. Priming is usually done with help of water pressure as per the description of your system’s user manual, but in the field water pressure may not be available, which is why you should get a special filter primer, which will force the air out of the pores. Alternatively, you can use the method described below (“How to Prime Your Filters in The Field?”);
  • Filter elements are cleanable: You can clean filter candles by holding them under running water and gently scrubbing them with a dishwasher sponge. This will extend their service life, but you should only reuse filter elements as per the description of the system’s user manual;
  • Chipped or otherwise damaged filter elements should be replaced: Since filter elements or filter candles are made of ceramics, you should handle them with care when you’re replacing them;
  • Clean the filter chambers: Other than replacing your filter candles at the required intervals, you should also clean the filter chambers to get rid of any dirt build-up or sediments.


How to Prime Your Filters in The Field?

If you’re in the field and you forgot to prime your filter under running water and you don’t own a primer, you may have to take a different approach to priming your filters. Bear in mind that the method described below will make your filter elements filter at around 50-75% efficiency, which means that they will purify water much slower as opposed to normally primed filters.

The reason why filter candles or elements have a microporous structure is to efficiently filter out pathogenic bacteria and other dangerous contaminants. However, this advantage is a possible setback for unprimed filters that need to be used in the field, where water pressure is unavailable.

Another issue is water tension, which varies from region to region and even from season to season. If the water tension is too high, it’s increasingly difficult for water to push air out of the tiny pores through the force of gravity alone. Field-priming your filter candles can be done by following the steps below:

  • If your system is assembled, disassemble it and use the lower chamber to soak the filter candles in water (Use a clean source of water. If only contaminated water is available, use a different container to soak the filters in.) for 45 to 60 minutes with the opening of the filter stem facing upwards. Don’t submerge the entire candle and make sure no water gets into the candle through the opening of the stem. You’ll want water to enter the candle through the micropores. Use a cup or something that puts weight on the candles, so they can stay in the water;
  • You can also use the opening of the stem as a straw to draw water inwards. This requires some strong lungs as you have to maintain constant pressure for 45 seconds to a minute;
  • Once the inside of the candle fills with water, you’ll notice how heavy the filter elements will become. Next, you’ll want to reassemble your gravity water filter, all the while keeping as much water as possible in the core of the filter elements (while re-assembling, keep the stems facing upwards);
  • Once the candles are installed, immediately pour the water from the lower chamber (or the separate container) into the upper chamber;
  • Let the water resulting from the first purification cycle run to waste, then refill the upper chamber with water you want to purify.

The mechanism behind this priming method relies on the interplay between the force of gravity and the hydraulic pull or water. As water within the core of the filter elements drips into the lower chamber, it pulls new water into the element creating a siphon effect.

Because this priming method takes about an hour, always check to see if your filters are primed before you go off-grid. Priming your filters without water pressure will have them functioning at reduced performance, which can be a huge disadvantage in time-sensitive cases.


Gravity water filters can be used for home water treatment and they do remove municipal water contaminants, but they’re designed mainly for off-grid use. They’re a reliable water purification solution when potable water is not available, and they can be used to create potable water from untreated water sources (streams, ponds, rivers, etc.).


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