The Survivalist Blog

When people ask where they should begin preparing, food storage is usually one of the first answers they hear.

Food is important, but safe drinking water is more urgent.

You may be able to go for weeks without food under the right conditions. You will not remain functional for long without water, and dehydration can become dangerous much faster during hot weather, illness, or physical exertion.

That means every preparedness plan should include:

• Water already stored and ready to drink
• More than one way to treat questionable water
• Containers for collecting and transporting water
• A dependable method of filtering sediment
• A backup method of killing disease-causing germs

Having a mountain of stored food without a dependable water plan is like trying to eat soup with a fork. You have part of what you need, but not enough to solve the problem.

This article explains how to build a simple two-bucket gravity water-filter system using commercially manufactured replacement filter elements.

This is not a pile of sand, charcoal, and gravel that magically turns contaminated water into safe drinking water. The buckets serve as the housing. The replaceable filter elements do the actual treatment.

Important: No water filter removes every possible contaminant. Follow the element manufacturer’s instructions and verify exactly what the elements are certified or tested to reduce. Water contaminated with fuel, pesticides, industrial chemicals, radioactive material, salt, or unknown toxic substances may require a completely different water source.

Water Filtration, Disinfection, and Purification Are Not the Same

The words filter, disinfect, and purify are often used as though they mean the same thing. They do not.

Filtration

Filtration physically removes particles and, depending on the filter’s pore size and media, may reduce certain parasites, bacteria, chemicals, tastes, and odors.

What a filter removes depends entirely on its design.

Disinfection

Disinfection kills or inactivates disease-causing microorganisms.

Common emergency disinfection methods include:

• Boiling
• Chlorine bleach used according to public-health instructions
• Chlorine dioxide
• Ultraviolet treatment in clear water

Purification

Purification is a broader term generally used when a treatment system reduces or removes particular contaminants to produce safer water.

Do not assume a product is a microbiological purifier merely because the seller calls it one. Look for independent certification and verify the exact claims.

For example:

• NSF/ANSI 42 generally covers aesthetic effects such as chlorine, taste, and odor.
• NSF/ANSI 53 covers specific contaminants with health effects.
• NSF P231 applies to microbiological water purifiers.

Certification to one standard does not mean a system removes every contaminant covered by every other standard.

What This Homemade Gravity System Actually Does

This system uses two food-grade buckets stacked on top of one another.

The upper bucket holds untreated water. Commercial filter elements are installed through its bottom. Water slowly moves through the elements and collects in the lower bucket, where it can be dispensed through a food-grade spigot.

The advantages include:

• No electricity required
• No connection to household plumbing
• Easy-to-find replacement housing parts
• Lower cost than many complete stainless-steel systems
• Easy transport and storage
• The ability to replace damaged buckets without replacing the filter elements

The disadvantages include:

• • The assembled bucket system itself is not independently certified as a complete unit.
  • Improper drilling or installation can cause leaks or allow untreated water to bypass the elements.
  • Plastic buckets can crack, warp, or retain odors.
  • The system must be cleaned and handled carefully to prevent recontamination.
  • Its capabilities are limited to the verified performance of the installed elements.

About ProOne Gravity Filter Elements

I currently use ProOne gravity filter elements in my own water-filter system.

ProOne replacement elements are designed for gravity-fed water systems and can be installed in a properly constructed two-bucket setup, provided the mounting holes, washers, and hardware match the manufacturer’s specifications.

Before using any filter element, check the manufacturer’s current information for:

• • • Installation and priming instructions
    • Independent certifications and laboratory testing
    • The specific contaminants it is designed to reduce
    • Rated capacity and replacement schedule
    • Cleaning and storage requirements
    • Whether it is suitable for the water source you intend to treat

No filter removes every possible contaminant. ProOne elements may reduce a wide range of contaminants, but you should still verify the current claims for the exact model you purchase rather than relying on an old product description or third-party sales listing.

Purchase replacement elements from ProOne or a reputable authorized seller. Counterfeit and imitation filters may look similar but may not provide the same performance.

Do not buy a filter solely because an online listing says that it “removes everything.”

Counterfeit and imitation replacement elements are also common. Buy from a reputable manufacturer or authorized dealer and verify the product before trusting it with your family’s drinking water.

What You Will Need

• • • Two new food-grade five-gallon buckets
    • Two tight-fitting food-grade bucket lids
    • One or more compatible gravity filter elements
    • A food-grade beverage spigot with washers and retaining nut
    • An electric drill
    • Drill bits or a step bit sized for the filter stems and spigot
    • A tape measure
    • A permanent marker
    • Food-safe sanitizer or unscented household bleach for sanitizing the buckets
    • Clean disposable gloves

Do not drill the holes based solely on measurements from an old article.

Filter stems and spigots vary. Measure the parts you actually purchase and follow the current instructions supplied by the manufacturers.

The hole must be large enough for the stem to pass through but not so large that the washer cannot seal it.

Use New Food-Grade Buckets

I recommend new buckets specifically sold for food storage or food handling.

A number 2 recycling symbol indicates that a bucket is made from high-density polyethylene. That symbol alone does not guarantee that the bucket was manufactured or handled for food use.

Never use a bucket that previously contained:

• • • Paint
    • Drywall compound
    • Cleaning products
    • Pesticides
    • Fertilizer
    • Motor oil
    • Pool chemicals
    • Solvents
    • Any unknown substance

Buckets from bakeries and restaurants may be suitable if they held only food, but strong odors from pickles, frosting, or other products may remain in the plastic.

For drinking water, new buckets remove that uncertainty.

Step 1: Clean and Sanitize Everything

Wash the buckets, lids, spigot, washers, and other washable parts with dish soap and clean water.

Rinse everything thoroughly.

Sanitize the buckets according to current CDC guidance or the bucket manufacturer’s instructions. Allow them to air-dry in a clean location.

Wash your hands before handling the cleaned parts. Avoid touching the inside surfaces of the lower bucket, the inside of the spigot, or the clean side of the filter elements.

Step 2: Mark the Filter Locations

Turn the upper bucket upside down.

Mark the locations where the filter elements will pass through the bottom.

Space the elements far enough apart that:

• • • The filter bodies do not touch.
    • The washers sit flat.
    • The retaining nuts or wing nuts can be tightened.
    • The stems align with openings in the lid below.

Keep the holes away from the curved outside edge of the bucket bottom. The washers need a flat surface to make a dependable seal.

Step 3: Drill the Upper Bucket

Drill the marked holes using the bit size recommended for your filter elements.

Drill slowly and keep the bit straight.

Remove all plastic shavings and smooth any sharp edges without enlarging the holes unnecessarily.

Wash and sanitize the bucket again after drilling. Plastic shavings must not be left inside the system.

Step 4: Prepare the Lower Bucket Lid

Place the drilled upper bucket on top of one lid and mark where the filter stems contact it.

Drill clearance holes through the lid so the stems and retaining hardware can extend through without supporting the weight of the upper bucket.

The upper bucket should sit securely and evenly on the lid of the lower bucket.

The holes in this lid do not filter anything. They merely allow treated water to drip into the lower chamber.

Step 5: Install the Spigot

Choose a location on the side of the lower bucket approximately two to three inches above the bottom.

Placing it slightly above the bottom:

• • • Gives the retaining nut room to fit inside
    • Reduces the chance of damaging the spigot when setting the bucket down
    • Leaves a small amount of sediment below the spigot if contamination enters the lower chamber

Drill the hole according to the spigot manufacturer’s specified diameter.

Install the washers in the order shown in the spigot instructions. Hand-tighten the retaining nut until the seal is snug.

Do not overtighten it. Excessive force can distort the bucket wall, crush the washer, crack the plastic, or create a leak.

Step 6: Install the Filter Elements

Prepare or prime the elements exactly as directed by the manufacturer.

Some carbon-block elements must be saturated or flushed before normal use. Others have different preparation requirements.

Insert each filter stem through the bottom of the upper bucket with the supplied washer in the correct position.

Install the retaining hardware from below.

Tighten it carefully by hand unless the manufacturer specifically instructs otherwise.

Overtightening can damage the filter stem, deform the washer, or crack the element.

Step 7: Assemble the Two Chambers

Place the drilled lid on the lower bucket.

Set the upper bucket on the lid, aligning the filter stems with the clearance holes.

Place the remaining lid over the upper bucket.

The complete arrangement should be:

• • 1. Upper lid
    2. Upper bucket holding untreated water
    3. Filter elements mounted through the upper bucket
    4. Drilled lower-bucket lid
    5. Lower bucket collecting treated water
    6. Spigot near the bottom of the lower bucket

Step 8: Test for Leaks and Bypass

Before trusting the system, add known safe tap water to the upper chamber.

Check:

• • • Around each filter stem
    • Around the spigot
    • The bottom and sides of both buckets
    • The lid connection between the two buckets

Water should pass through the filter media—not around the filter stems.

If untreated water leaks around a washer or stem, stop using the system. Drain it, correct the installation, sanitize the affected parts, and test it again.

Follow any integrity or performance test supplied by the filter manufacturer. Do not invent a test or assume that clear-looking water proves the element is working.

How to Use the Gravity Filter

Pour source water into the upper chamber and replace the lid.

Allow gravity to move the water through the elements into the lower chamber.

Flow will normally be faster when the upper bucket is full because greater water pressure is placed on the elements.

Do not allow the lower chamber to overfill. If both chambers are full at the same time, untreated water may leak from the upper bucket or contaminate the outside of the lower chamber.

Dispense the treated water through the spigot without placing dirty cups, hands, or utensils against the opening.

Start With the Cleanest Water Available

A filter lasts longer and works more effectively when the source water contains less sediment.

If the water is muddy or cloudy:

• • 1. Allow heavy material to settle.
    2. Carefully pour off the clearer water.
    3. Prefilter it through a clean cloth, coffee filter, or other sediment prefilter.
    4. Then place it into the gravity-filter system.

Prefiltering removes dirt and debris. It does not make contaminated water safe to drink by itself.

Do You Still Need to Boil or Disinfect the Water?

Possibly.

The answer depends on:

• • • The source of the water
    • The filter element
    • The filter’s certified capabilities
    • The possibility of viral contamination
    • Local public-health instructions

CDC guidance warns that portable filters do not remove every type of germ. Many filters do not remove viruses, and some remove parasites more effectively than bacteria.

If the source may contain disease-causing germs and your filter is not independently certified as a microbiological purifier for those organisms, use an additional treatment step.

Boiling is the most dependable household method for killing germs:

• • • Bring clear water to a rolling boil for one minute.
    • At elevations above 6,500 feet, boil it for three minutes.
    • Allow it to cool naturally.
    • Store it in a clean, sanitized, covered container.

Follow local health-department instructions during a boil-water notice or declared emergency.

What This System Cannot Make Safe

Do not use this filter and assume that it will make every source drinkable.

Ordinary gravity filters generally cannot make water safe when it contains dangerous levels of:

• • • Gasoline or diesel fuel
    • Pesticides
    • Industrial chemicals
    • Radioactive material
    • Saltwater
    • Unknown chemical waste

Boiling can make some chemical problems worse by evaporating water and concentrating the contaminant that remains.

If you suspect chemical, fuel, or radioactive contamination, use commercially bottled water or another known-safe source and contact public-health authorities.

Keep the Clean-Water Chamber Clean

Once water has been treated, careless handling can contaminate it again.

To prevent that:

• • • Keep the lower bucket covered.
    • Do not reach into it with your hands.
    • Do not dip cups or scoops into it.
    • Keep the spigot clean.
    • Do not set the system beside chemicals, garbage, or raw food.
    • Clean and sanitize the lower chamber periodically.
    • Do not allow pets or children to play with the spigot.

If the treated water develops an unusual odor, taste, cloudiness, or visible growth, stop using it until the system has been cleaned, inspected, and the filter elements evaluated.

Filter Maintenance

Follow the element manufacturer’s instructions for:

• • • Cleaning
    • Priming
    • Storage
    • Maximum capacity
    • Replacement intervals
    • Freezing precautions
    • Integrity testing

Do not judge filter life only by the number of gallons advertised.

Dirty source water, heavy sediment, unusual contaminants, improper cleaning, freezing, physical damage, and long periods of storage may shorten the useful life.

Keep a written record of:

• • • Installation date
    • Type of filter element
    • Approximate gallons filtered
    • Cleaning dates
    • Problems or changes in flow

Emergency Water Storage

A filter is not a substitute for storing water.

During an emergency, the safest and easiest water to use is water that was already safe when you stored it.

The CDC recommends storing at least one gallon of water per person per day for three days. When possible, try to build a two-week supply.

Store more for:

• • • Hot climates
    • Pregnant or nursing women
    • People who are ill
    • People doing heavy physical work
    • Pets and livestock
    • Cooking and sanitation

For a family of four, a basic two-week supply is:

4 people × 14 days × 1 gallon = 56 gallons

That is why relying on one or two cases of small bottles is not a complete water plan.

Choosing Water-Storage Containers

The best choices include:

• • • Unopened commercially bottled water
    • Food-grade water-storage containers
    • Heavy-duty five- or seven-gallon portable water containers
    • Food-grade 55-gallon water barrels when space and floor strength permit

Used two-liter soda bottles can provide inexpensive short-term storage when they are thoroughly cleaned and sanitized.

Do not use containers that previously held milk, juice, chemicals, pesticides, fuel, or cleaning products.

Milk jugs are especially poor long-term containers. They are thin, difficult to sanitize completely, and prone to leaking.

Glass is chemically stable but heavy and easily broken. It may not be practical where earthquakes, children, pets, or frequent handling are concerns.

Storing Municipal Tap Water

If your municipal tap water is currently safe to drink, it can be placed into properly cleaned and sanitized food-grade containers.

Municipal water normally already contains a disinfectant, so additional bleach is not automatically necessary when initially filling the container with safe tap water.

However, the container must still be clean and sanitized, and the water can become contaminated during filling or storage.

CDC guidance recommends:

• • • Labeling each container as drinking water
    • Writing the storage date on it
    • Replacing home-filled water every six months
    • Keeping it in a cool location, ideally around 50°F to 70°F
    • Protecting it from direct sunlight
    • Keeping it away from gasoline, pesticides, cleaners, and other toxic substances

Always follow local health-department instructions if your water utility issues a boil-water or do-not-use notice.

Have More Than One Water-Treatment Method

No single piece of equipment should be your entire water plan.

I recommend having:

• • • Stored drinking water
    • A gravity filter
    • A portable filter for evacuation or travel
    • A large pot and fuel for boiling
    • Unscented household bleach suitable for water disinfection
    • Chlorine-dioxide tablets or another backup treatment
    • Clean collection containers
    • Cloth or coffee filters for removing sediment

Know how to use everything before an emergency occurs.

The Bottom Line

A two-bucket gravity system can be an affordable and useful part of an emergency water plan.

The buckets provide the upper and lower chambers. The commercially manufactured filter elements provide the actual treatment.

Do not assume the system makes every water source safe. Verify the elements’ current certifications and contaminant-reduction claims. Install them correctly, test for leaks and bypass, keep the clean-water chamber sanitary, and use an additional disinfection method when the water may contain germs the elements are not certified to remove.

Most importantly, store water before you need it.

A filter gives you options, but already having safe water on hand gives you time—and time is one of the most valuable things you can have during an emergency.

Have you built a bucket-style gravity filter, and what water-storage methods have worked best for your household? Add your thoughts below.