What is a gravity filter? Everything you need to know

A gravity filter is a simple and standalone water purification system that uses the force of gravity to pass water through one or more filter cartridges. This is how it removes contaminants that may harm your health.

The gravity filter differs from a regular water filter that uses a pump or the pressure of the water supply to force water through the filters. The spectrum of contaminants it removes is also very broad. This article explains everything you need to know about gravity filters, from their usefulness to selection criteria and how they work.

When to use a gravity filter?

Gravity filters are commonly used to treat rainwater, spring water, or tap water when its quality is questionable. Thus, they prove to be very useful both at home and in remote areas, during hikes and in emergency situations.

Domestic applications of the gravity filter

Gravity filters offer a simple and effective solution for purifying drinking water in your home. The filtered water from your gravity water filter is often remineralized, making it tastier for preparing tea, coffee, and other hot beverages.

In the kitchen, water collected from a gravity filter is:

• Ideal for cooking, preparing rice, pasta, and other foods. Indeed, it is free from contaminants that could affect the taste or quality of food.

• Safer for washing fruits and vegetables, as it reduces the risk of ingesting harmful chemicals or bacteria present in water.

• Exempt of chlorine that affects the smell and taste of water, as well as other chemicals that may harm indoor and outdoor plants.

Drinking water treatment in remote areas

In many remote areas of the world, access to safe and reliable drinking water remains a major challenge. Gravity filters then provide a practical, effective, and affordable alternative for purifying drinking water.

Indeed, untreated water sources can be contaminated by various pathogens: bacteria, viruses, parasites, etc. This leads to a wide range of serious illnesses, including diarrhea, cholera, and typhoid.

By promoting access to safe drinking water, gravity filters significantly help reduce these waterborne diseases, thereby improving the overall health and well-being of communities.

Use in emergency situations and hiking

Whether during a natural disaster, infrastructure failure, or an outdoor excursion, access to drinking water becomes a matter of survival. In these situations, gravity filters prove to be valuable tools for purifying water and making it safe for consumption.

Indeed, many gravity filter models are compact and lightweight, making them ideal for carrying on hikes, camping trips, and emergency situations.

How does a gravity filter work?

A typical gravity filter consists of two stacked compartments. Untreated water is poured into the upper compartment, then flows through one or more filters before being collected in the lower compartment, ready for consumption.

Multilayer technology for pure water

Gravity filters use a combination of techniques to remove a wide spectrum of contaminants from water, including:

• Microfiltration : Tiny pores capture pathogens, cysts, parasites, and microscopic impurities, forcing the water to follow a winding path that traps them.

• Adsorption and absorption : The filtering media attracts and retains contaminants through chemical bonds, eliminating even submicronic viruses that other filters cannot capture without chemicals.

Optimized flow rate for effective purification

Unlike other systems that force water through filters at high pressure, gravity filters use gravity for prolonged contact between the water and the filtering media. This slow and effective approach maximizes the capture of contaminants.

The filtering materials may include:

• ceramic,

• activated carbon,

• hollow fiber and other substances.

Each material has its own filtration properties, allowing for targeting a wide range of impurities.

Result: Clean and safe drinking water

By combining these techniques, the gravity filter system offers a comprehensive solution for purifying water from various sources, reducing:

• sediments and suspended particles,

• bacteria and viruses,

• parasites,

• chemical substances, pesticides, and herbicides,

• chloride and other undesirable chemicals,

• unpleasant tastes and odors.

What are the types of gravity filters?

Gravity filters come in different varieties based on the number of tanks and filtration technologies.

Types of gravity filters according to the number of tanks

There are gravity filters designed with a single tank for easy transport and others with two tanks to optimize filtration.

Single-tank gravity filters

They are designed for easy and convenient outdoor use: simply hang the filtering tank using a strap and open the tap for the water to flow. There is a hydration hose provided to facilitate filling bottles and flasks. You can also control the flow with the On/Off valve.

Two-tank gravity filters

Gravity water filters made of two stacked tanks are the most common. They generally have 2 filtration cartridges. Some models can accommodate 3 or 4 filtering cartridges depending on the quality of the water.

Untreated water is poured into the upper tank, while filtered and purified water is collected in the lower tank so that you can access it.

Types of gravity filters according to filtering materials

Gravity filters can also be classified according to the different types of filtering materials used to capture and remove contaminants from water.

Activated carbon filtration

Activated carbon attracts and retains organic impurities, chemicals, odors, and unpleasant tastes through adsorption. However, it is less effective against bacteria and viruses. That is why at Weeplow, we combine it with various other technologies in our O'Pure 2.

Ceramic filtration

Ceramic filters consist of tiny pores that capture bacteria, protozoa, and other suspended particles through physical filtration. They effectively remove microorganisms, are durable, and resistant to contamination.

Unlike carbon filters that require a priming step before use, ceramic filters are ready to use right out of the package. This makes them more convenient and easier to use, especially in emergency situations.

However, these types of water filters are less effective against chemicals and odors. Similarly, the water flow may be slower.

Membrane filtration

These types of gravity water purifiers use a porous membrane to remove contaminants from water. They provide precise filtration against microorganisms and smaller contaminants.

Indeed, membranes can be:

• In microfibers : Made from fine synthetic fibers, they retain suspended particles like sand, mud, and protozoa.

• In ceramic : Offering finer filtration, they remove bacteria and viruses in addition to suspended particles.

Naturally, the pore size of the membrane determines the size of the contaminants that can be removed. Membranes can last for several years with proper maintenance.

What are the advantages of a gravity filter?

Gravity filters offer many advantages for purifying water at home or on the go, including:

• ease of use,

• filtration efficiency,

• autonomy and versatility,

• sustainability and profitability,

• sustainable approach to access drinking water.

You can browse our dedicated article to discover all the advantages of a gravity filter.

What are the criteria for choosing a gravity filter?

The choice of a gravity water filter mainly depends on your daily water needs, the intended use, and your budget.

How to choose the size of your gravity filter?

The size of a filter determines the amount of water it can hold at one time. This criterion is particularly important for filters that include a tank, such as gravity filters.

Here are some points to consider when choosing the appropriate storage capacity:

Your daily water consumption

The more water you consume, the greater the storage capacity of your gravity filter needs to be. If you have a large family or use a lot of water for cooking, opt for a model with a substantial tank.

The World Health Organization (WHO) recommends an average consumption of about 2 liters of water per day per person to stay hydrated. For a family of 4, this represents a daily need of about 8 liters of drinking water.

Of course, this calculation is an estimate and can vary based on factors such as climate, physical activity, and individual habits.

The frequency of use

If you plan to use your drinking water filter daily, you should opt for a large capacity. If you use it occasionally, a smaller filter may suffice.

Do you live in an area where water outages are frequent? Then, a filter with a large storage capacity (22 liters for example) can ensure you have a supply of drinking water even during an outage.

The number of users

The more people using the water filter, the greater the storage capacity needs to be. For a single person, a filter of 2 to 4 liters may suffice. However, if you have a family of 4, a size of 5 to 8 liters is generally recommended.

For larger groups or heavy use, opt for a filter of 10 liters or more. In this regard, the largest water filter Weeplow has a capacity of 11 liters, larger capacity models will be marketed soon!

The available space for the water filter

When choosing a fixed filter model, you need to consider the intended location, whether on a countertop or a shelf. Don't forget to allow extra space for filling the tank and replacing the filter cartridges. Some models even come with a non-slip base and a stainless steel support with 4 legs.

If you have limited space, opt for a compact gravity filter with a smaller tank. You might consider a 5.6 liter gravity filtration system.

Do you want additional features like a built-in faucet or a high stand? Then, make sure the chosen filter fits the available space with these elements without obstructing movement or work in the kitchen.

How to choose your gravity filter based on usage?

The choice of a gravity filter also depends on the main use you will make of it. For example, when your tap water is of good quality, a simple model with an activated carbon filter may be sufficient to eliminate the taste of chlorine, impurities, and chemicals.

If your source water is questionable or comes from a private well, then consider a model with multiple filtration stages, including an O'Pure 2B filter. This is recommended to eliminate arsenic and fluorides.

Are you planning to go camping or hiking? In that case, a portable and lightweight gravity filter is essential. Generally, you can easily attach it high up on a tree to have a drinking water point at your campsite. 

How to assess the necessary water flow rate for your gravity filter?

The flow rate is an element not to be overlooked when looking for a water filter that will meet your daily needs. It is the amount of water treated in a unit of time, usually expressed in liters per hour.

Imagine you have a high water consumption, for example in a house with several occupants or if you use the filter for cooking. In these cases, a high flow rate is essential to avoid waiting times and frustrations.

To determine the minimum flow rate required for your situation, follow these steps:

• Estimate your total daily water consumption, not forgetting cooking and cleaning.

• Determine the daily usage duration of the water filter.

• Divide the total water consumption by the duration of use.

The result corresponds to the minimum flow rate required in liters per hour. For example, for a total daily consumption of 8 liters and a daily usage duration of 8 hours, you need a minimum flow rate of 1 liter/hour.

At Weeplow, our two-filter systems offer a flow rate of up to 3.8 liters per hour, which is fast enough to meet all usage cases.

How much does a gravity filter cost?

The price of a gravity water filter typically ranges from 130 euros to 500 euros depending on the following factors:

• Tank capacity : Filters with larger tanks are generally more expensive.

• Laboratory tested filters: The tested filters whose effectiveness is approved by laboratories.

• The manufacturing material : A water filter where each fountain is made of stainless steel will cost more than a model made of plastic.

• Additional features : Features like a faucet with a water level gauge or a 4-foot stand.

Which gravity filter to choose according to your needs? (comparison)

This comparative guide presents some popular brands, including the French brand Weeplow. It highlights the main features of the items to help you make an informed choice.

	Weeplow	British berkefeld	Berkey
Price of the entire filter (tank + cartridges)	179,99€ - 219,99€	179,90€ - 419,90€	265€ - 542€
Technology used	O’Pure 2 in natural coconut activated carbon	Ultra Sterasyl ceramic	Coconut charcoal and ionized silver
Elements removed	Viruses, cysts and pathogenic bacteria such as e-coli, parasites, harmful or undesirable chemicals such as herbicides and pesticides, COV, detergents, organic solvents, trihalomethanes, sediments, nitrates, nitrites, heavy metals, bad tastes and odors.	Bacteria, cysts, chlorine and derivatives, salmonella, giardia, cryptosporidiosis, organic substances, pharmaceuticals, heavy metals (lead, arsenic...) PFAS, pesticides, herbicides, insecticides, microplastics, hydrocarbons, bad tastes and odors.	Viruses, pathogenic bacteria including e. coli, cysts, parasites, radiological products, disinfectants, non-metallic inorganic minerals, heavy metals, pharmaceutical residues and contaminants, pesticides, petroleum residues, VOCs.
Price and duration of a pair of cartridges	99.99€, to be replaced after 22,700 liters of filtered water	69€, to be replaced after 3,000 liters of filtered water	185€, to be replaced after 22,700 liters of filtered water
Available sizes	5.6 L, 8.5 L, 11 L	1 L, 6 L, 8.5 L, 12 L	0.95 & 0.6 L, 5.7 L, 8.5 L, 12.3 L, 17 L, 22.7 L
Highest flow rate	3.8 Liters per hour	2 Liters per hour	3.8 Liters per hour
Pack contents	› 2 AISI 304 stainless steel tanks with lid › 2 O’Pure 2 purification elements › 1 stainless steel tap with water level indicator › 1 key for tap installation › 2 caps to fill the unused passages of the upper tank › 1 non-slip support › 1 stainless steel support with 4 legs	› Upper and lower tanks in AISI 304 stainless steel › Lid › Non-slip gasket › Two Ultra Sterasyl filters with washers and wing nuts  › Food-grade plastic tap › Instructions in 5 languages › Stainless steel tap included	› 2 purification elements (filters) " Black Berkey " › 1 lower water storage tank in stainless steel  › 1 tap, › 1 upper tank and its lid, both in stainless steel › 1 handle › 1 priming cap  › 1 new quick start kit › 2 notices, in French and in English
Unique advantage	Best value for money and compatible with Ultra Sterasyl, Ultra Fluoride, Black Berkey® filters	Compatible with Ultra Sterasyl, Ultra Fluoride, Black Berkey® filters	High capacities and flows

How to maintain and clean a gravity filter?

Maintaining and cleaning your gravity water filter is essential to ensure the purity of drinking water. You should perform regular inspections to detect any debris, sediments, or damage that may affect filtration efficiency.

The frequency of cleaning the filter elements depends on your water consumption and the quality of your water source. In general, monthly cleaning is recommended. Clean more often if you notice a decrease in water flow.

Here’s how to proceed with disassembly and cleaning:

• Wash your hands before handling the filter elements.
• Empty the remaining water from the upper tank.
• Unscrew the wing nut and remove the washer.
• Remove and rinse the elements thoroughly with clear, lukewarm water.
• Use a soft toothbrush to remove visible debris and sediments.
• Never use hot water or vinegar spray, as this could damage the filter elements.
• Rinse the elements thoroughly after brushing.

Additionally, regularly wipe the outside of the container with a damp cloth to remove dust and fingerprints.

Find the gravity water filter that suits you

Now, you have all the answers to the question of what a gravity filter is. Its usefulness is undeniable both at home and while traveling. You can choose from a multitude of models and brands to start enjoying the benefits of this sustainable approach to accessing drinking water.

At Weeplow, we offer a variety of sizes of water filtration systems to suit all needs and budgets. Our technology can reduce up to 99.999% of harmful contaminants in water. 

Browse our shop online to find the custom-sized filter for your home.