How to Add a Potable Water Treatment System to an IBC Tote Rainwater System
Turning a pressurized rainwater supply into a separately treated line for drinking and cooking
Our original rainwater catchment system was designed around two connected 275-gallon IBC totes, a pump, pressure tank, pressure gauge, sediment filtration, a cabin supply line and an outdoor hose connection.
That system gives us approximately 550 gallons of stored rainwater and allows us to move it under pressure. However, collecting, pumping and filtering rainwater does not automatically make it safe to drink.
Rainwater can collect bacteria, parasites, viruses and chemical contaminants from the air, roof, gutters, storage tanks and plumbing. Even clear water with no unusual taste or odor may still contain contaminants that could cause illness.
In this companion project, we will add a separate treatment branch for water intended for:
Drinking
Cooking
Making ice
Brushing teeth
Washing produce
Other uses in which water may be swallowed
Because every roof, storage system and water source is different, this article explains the layout and planning process rather than prescribing one universal filter combination.
An important distinction
The three-stage filter mounted along the outside of our cabin can remove sediment and may improve the water’s appearance, taste or odor, depending on the cartridges installed. However, ordinary sediment and carbon filters alone should not be treated as proof that rainwater is potable.
Different treatment technologies remove different contaminants. A filter that removes sediment may not remove viruses. Activated carbon may reduce certain chemicals, odors and tastes but does not reliably disinfect the water. Ultraviolet treatment can inactivate microorganisms when properly sized and operated, but it does not remove dissolved chemicals. Reverse osmosis can remove many dissolved contaminants, but its performance depends on the membrane, operating pressure and the contaminants present.
The treatment system must therefore be selected after considering:
The quality of the collected water
The intended use
The results of laboratory testing
The required flow rate
Local plumbing and health requirements
Check local requirements before connecting the system
Before piping treated rainwater to a kitchen sink or another potable fixture, contact the local building department or environmental-health office.
Georgia currently uses the 2024 International Plumbing Code with Georgia amendments effective in 2026, and the state’s mandatory construction codes apply statewide. Local authorities may also have administrative, inspection, permitting, backflow-prevention and water-treatment requirements.
Tell the local authority that you are proposing:
A residential rainwater-harvesting system with atmospheric storage tanks, a pump and pressure tank, a separate potable-water treatment branch, and dedicated drinking-water fixtures.
Ask specifically:
Whether potable rainwater use is permitted at the property
Whether a plumbing permit is required
Which treatment and testing standards apply
Whether plans must be submitted
Which backflow or cross-connection devices are required
Whether the system must be installed or inspected by a licensed professional
Whether ongoing water testing is required
Do this before purchasing expensive treatment equipment.
Keep the potable and nonpotable branches separate
The pressurized line leaving the pump can divide into separate branches:
TWO IBC TOTES
↓
Coarse pump strainer
↓
Water pump
↓
Pressure tank, switch and gauge
↓
Initial sediment protection
↓
Distribution manifold
├── Nonpotable cabin fixtures
├── Garden-hose connection
└── Potable treatment branch
↓
Dedicated shutoff valve
↓
Treatment system
↓
Potable kitchen fixtureThe potable branch should have its own:
Full-port shutoff valve
Union or removable fittings
Drain or depressurization point
Treatment equipment
Sampling tap
Dedicated plumbing line
Clearly identified fixtures
Rainwater must not be able to flow backward into a municipal or well-water plumbing system. The CDC warns that mixing untreated rainwater with previously treated water can contaminate the safe supply.
Do not connect rainwater and public or well water through an ordinary tee with two shutoff valves. A valve can leak, fail or be opened accidentally. Any backup-water arrangement should be designed with the approved air gap or backflow protection required by the local authority.
Step 1: Protect the source water
Potable treatment begins at the roof, not at the kitchen sink.
The cleaner the water entering the totes, the easier it will be for the final treatment system to work reliably.
The collection system should include:
A suitable roof surface
Clean gutters
Leaf guards
Downspout screening
A first-flush diverter on each downspout
Screened tank inlets
Mosquito-proof vents
Screened overflows
Opaque or fully shaded storage tanks
A way to inspect and clean the tanks
A first-flush diverter directs the initial and most contaminated runoff away from storage. That early runoff can carry dust, pollen, bird droppings and other debris accumulated on the roof between storms.
No first-flush system removes every possible contaminant, but reducing contamination at the source protects the tanks and extends filter life.
Step 2: Confirm that every material is appropriate
Use only IBC totes with a known history. A tote previously used for industrial chemicals, pesticides, fuel or an unknown substance should never be converted into drinking-water storage.
For the potable portion of the system, use tanks, pipes, valves, fittings, filter housings, sealants and other wetted components approved for drinking-water contact. Look for the appropriate certification for the particular component, commonly including NSF/ANSI/CAN 61 for drinking-water system materials.
A component being sold in a plumbing aisle does not necessarily mean it is approved for potable-water contact.
Roofing and gutter materials matter as well because rainwater can pick up chemicals such as lead, copper and other substances as it passes across collection surfaces.
Step 3: Test the untreated rainwater
Before selecting the final treatment equipment, collect a representative sample from the stored water and send it to a qualified laboratory.
Contact the county environmental-health office or an accredited drinking-water laboratory for instructions. Ask which tests are appropriate for locally collected rainwater.
A starting test panel may include:
Microbiological testing
Total coliform bacteria
E. coli
Other organisms recommended by the laboratory or health department
Basic water characteristics
pH
Turbidity
Color
Odor
Hardness
Total dissolved solids
Chemical testing based on local risks
Lead
Copper
Arsenic
Nitrates and nitrites
Roofing-related metals
Volatile organic compounds
Pesticides or herbicides
Other locally relevant contaminants
The correct testing list depends on the roofing, gutters, nearby land use, air quality, tank history and local environmental conditions.
The CDC recommends regular testing for germs and chemicals when rainwater is used for drinking, cooking or bathing. Private rainwater systems are not routinely monitored in the way that public water systems are.
Step 4: Build the treatment system in stages
A potable rainwater treatment train generally works from coarse treatment to fine treatment, followed by disinfection.
A practical conceptual arrangement is:
Pressurized rainwater supply
↓
Potable-branch shutoff valve
↓
Washable coarse sediment filter
↓
Fine sediment cartridge
↓
Carbon or contaminant-specific treatment
↓
Final fine prefilter
↓
Validated disinfection
↓
Sampling tap
↓
Dedicated kitchen drinking-water lineThe exact cartridges and equipment must be selected from the water-test results and manufacturer specifications.
Stage A: Coarse sediment filtration
The first filter protects the finer treatment equipment from sand, grit, rust particles, organic debris and sediment.
A washable spin-down or screen filter is useful because it can be flushed without repeatedly replacing a cartridge.
This stage should not be mistaken for microbial treatment. Its job is primarily to reduce larger particles and protect the equipment that follows.
Stage B: Fine sediment filtration
The next stage reduces smaller suspended particles and lowers turbidity.
The required micron rating depends on:
The source-water quality
The final disinfectant
The manufacturer’s requirements
The desired flow rate
Fine filters become restrictive as they collect sediment. Install pressure gauges before and after the filter bank, or use housings with pressure-monitoring ports, so you can recognize when cartridges are clogging.
Do not choose an extremely fine cartridge without checking whether the pump can maintain the required flow and pressure.
Stage C: Carbon or contaminant-specific treatment
Activated carbon may be used to reduce certain tastes, odors and organic chemicals. It can improve the finished water, but it should not be treated as the system’s primary disinfectant.
Carbon can also become a place where microorganisms grow when it is not changed and sanitized properly. Replace cartridges according to measured use, pressure loss, water quality and the manufacturer’s schedule.
Laboratory results may indicate that a different or additional treatment is needed, such as:
Lead-reduction media
Specialized metal-removal media
Nitrate treatment
Reverse osmosis
Ion exchange
Other contaminant-specific equipment
A water-treatment professional can match certified equipment to the contaminants actually present. The CDC recommends choosing treatment based on testing rather than relying on appearance, taste or a generic filter claim.
Stage D: Final disinfection
Filtration removes material from water. Disinfection addresses living microorganisms.
Common residential disinfection approaches include:
Ultraviolet light
Chlorination
Ozone
A properly engineered combination of treatments
The correct choice depends on the system, local requirements and how water is distributed after treatment.
Ultraviolet disinfection
UV systems expose flowing water to ultraviolet light to inactivate microorganisms.
For drinking-water treatment, use a unit specifically certified and sized for the purpose, not a decorative aquarium or pond UV light. Where a potable rainwater system relies on UV, an NSF/ANSI 55 Class A unit is a widely recognized benchmark for microbiologically unsafe water.
UV performance depends on:
Water clarity
Turbidity
Flow rate
UV transmittance
Lamp strength
Cleanliness of the quartz sleeve
Electrical power
Proper pretreatment
A UV unit cannot disinfect water effectively when sediment shields microorganisms from the light. That is why final fine filtration normally comes before UV treatment.
UV also leaves no disinfectant residual in the plumbing after the water passes the lamp. Water can therefore be recontaminated downstream if pipes, faucets or storage vessels are dirty.
Chlorine disinfection
A properly designed chlorination system can disinfect water and leave a residual that continues protecting the distribution plumbing.
However, chlorination requires more than occasionally pouring bleach into an IBC tote. A functioning system may require:
Controlled chemical dosing
Accurate concentration
Contact time
A contact tank
Residual monitoring
Safe chemical storage
Periodic verification
Treatment for taste or disinfection byproducts where needed
Chlorine can kill many harmful organisms, but it is less effective against some resistant parasites, and adding disinfectant does not remove chemical contamination.
Because dosage and contact time are safety-critical, continuous chlorination should be designed with qualified guidance.
Would reverse osmosis make the water safe?
Reverse osmosis can remove many dissolved contaminants and is commonly used as a final point-of-use treatment under the kitchen sink.
However, an RO system should not be installed as the only treatment placed directly after an IBC tote. Sediment, microorganisms and organic material can clog or damage the membrane.
A whole-system arrangement might use:
Sediment pretreatment
↓
Carbon or contaminant-specific treatment
↓
Disinfection
↓
Potable plumbing
↓
Optional under-sink reverse osmosis
↓
Dedicated drinking-water faucetWhether RO is needed should be determined by the water-test results. It wastes part of the incoming water as concentrate and requires sufficient pressure, drainage and maintenance.
Step 5: Install the potable branch
The potable treatment branch should begin after the pump and pressure tank so the treatment equipment receives controlled pressure.
A suggested component order is:
Main pressurized manifold
↓
Dedicated potable-line shutoff valve
↓
Union
↓
Pressure gauge
↓
Coarse sediment filter
↓
Fine sediment filter
↓
Carbon or contaminant-specific cartridge
↓
Final prefilter required by disinfectant
↓
UV or approved disinfection system
↓
Sampling tap
↓
Second pressure gauge, where useful
↓
Dedicated kitchen drinking-water lineFollow the manufacturer’s requirements for:
Maximum and minimum pressure
Maximum flow rate
Pipe size
Filter orientation
UV chamber orientation
Electrical installation
Drainage
Required clearances
Cartridge replacement
Sanitizing
The potable-treatment equipment should be protected from rain, freezing, flooding, insects and direct sunlight while remaining accessible for maintenance.
Step 6: Add a sampling tap
Install a small sampling faucet immediately after the complete treatment train and before the water enters the long distribution line.
This allows you to test:
Untreated tank water
Water after treatment
Water at the kitchen faucet
Testing multiple points helps identify whether a problem originates in the source water, treatment equipment or household plumbing.
The sampling tap should be cleanable and positioned where a sterile sample bottle can be filled without touching the faucet to the container.
Step 7: Prevent untreated bypasses
Any bypass around the potable treatment system creates an opportunity for untreated water to reach the drinking faucet.
A service bypass can be useful when replacing filters, but it should not be arranged so untreated water can accidentally feed the potable line.
Safer options include:
No bypass at all
A lockable bypass
A removable pipe section
Valves requiring a deliberate multi-step procedure
A bypass that feeds only a clearly marked nonpotable outlet
If the UV light loses power, the lamp fails or flow exceeds the system’s rated capacity, the system should prevent untreated water from quietly continuing to the drinking tap. Depending on the equipment, this may involve:
An automatic shutoff valve
UV intensity monitoring
Audible and visual alarms
Lamp-failure protection
A flow-control device
Step 8: Sanitize before placing the system in service
New plumbing is not automatically clean.
Before drinking the treated water:
Clean the gutters, diverters and tank inlet screens.
Remove accumulated sediment from the totes.
Install new treatment cartridges.
Sanitize the tanks and potable plumbing using an approved procedure.
Flush the system thoroughly.
Operate the treatment equipment according to its manual.
Collect treated-water samples.
Wait for acceptable laboratory results before using the water for drinking.
The exact sanitizing method and concentration should come from the tank, filter, plumbing or public-health guidance applicable to the system. Do not mix chemicals or guess at concentrations.
Step 9: Test the treated water
A new treatment system should be tested before anyone relies on it.
Test the water:
Before treatment, to establish the source quality
After the treatment system is installed
After repairs or major alterations
After contamination, flooding or animal intrusion
After the system has been unused for an extended period
Whenever taste, odor, color or turbidity changes
At least annually, even when nothing appears wrong
More frequent microbiological testing may be appropriate, especially during the first year while you learn how the system behaves through different seasons and weather conditions.
The CDC recommends testing rainwater used for drinking at least once each year and considering additional testing whenever the water changes in appearance, smell or taste.
Step 10: Create a maintenance record
A potable-water system is not a one-time installation. It is an ongoing responsibility.
Keep a written record of:
Laboratory results
Filter model numbers
Cartridge micron ratings
Cartridge changes
UV lamp changes
Quartz-sleeve cleaning
Chlorine residual readings, where applicable
Tank cleanings
Gutter and first-flush maintenance
Repairs and plumbing changes
Periods when the system was shut down
Dates of sanitizing
Label each filter housing with the cartridge type and installation date.
Suggested maintenance schedule
After major storms
Inspect:
Roof and gutters
Leaf screens
First-flush diverters
Tote inlets
Overflow screens
Water clarity
Pump strainer
Monthly
Check:
Leaks
Pressure gauges
Filter pressure loss
UV indicator or disinfectant equipment
Tank covers and screens
Unusual taste, odor or color
According to equipment instructions
Replace or service:
Sediment cartridges
Carbon cartridges
Specialty media
UV lamp
Quartz sleeve
Reverse-osmosis membrane
Chemical feed equipment
At least annually
Test the untreated and treated water
Inspect and clean the storage system
Sanitize the potable plumbing as appropriate
Review whether the treatment equipment still matches the test results
What happens during a power outage?
A UV system requires electricity. The pump may also require electricity unless the system has a backup supply.
After a prolonged outage:
Do not assume water that passed through an inactive UV chamber was disinfected.
Close the potable-line valve if the system has no automatic shutdown.
Restore power.
Verify the UV unit is operating normally.
Flush water that may have bypassed effective treatment.
Follow the manufacturer’s restart or sanitizing procedure.
A battery backup, generator or solar-backed electrical system may help, but the UV unit must receive stable power that meets its specifications.
What happens when the totes run low?
Install dry-run protection for the pump, but also consider the effect of low water levels on quality.
Sediment commonly accumulates near the bottom of a storage tank. Drawing the totes nearly empty may pull more material toward the pump and shorten filter life.
A floating intake can sometimes draw water from below the surface rather than directly from the sediment layer at the bottom. Whether that arrangement is appropriate depends on the tank design and pump configuration.
A simpler alternative: treat only one faucet
Treating every gallon used in the cabin is not always necessary.
A practical arrangement is:
Nonpotable rainwater for gardening and outdoor cleaning
A separately treated line for bathing or toilet flushing, where permitted
A carefully designed point-of-use system serving only the kitchen drinking-water faucet
This reduces:
Filter size
Cartridge costs
UV flow requirements
Amount of water requiring the highest level of treatment
Maintenance burden
However, the source water and plumbing still require proper control because the drinking faucet must never receive untreated water.
Final system layout for our cabin
Our planned arrangement can be illustrated as follows:
LEFT IBC TOTE RIGHT IBC TOTE
│ │
Individual shutoff Individual shutoff
│ │
└──────── Common manifold ─────────┘
↓
Pump strainer
↓
Pump
↓
Pressure tank, switch and gauge
↓
Main sediment protection
↓
Distribution manifold
┌─────┴─────────────┐
│ │
Nonpotable branch Potable branch
│ │
Bathroom/hose/garden Shutoff valve
↓
Fine filtration
↓
Contaminant treatment
↓
Disinfection
↓
Sampling tap
↓
Dedicated kitchen faucetThe potable line will enter the treatment system near the rear of the cabin and then continue along the exterior toward the kitchen. The outside pipe and treatment equipment will eventually be enclosed and insulated for winter protection, while remaining accessible for filter changes, testing and repairs.
Final safety reminder
A filtration system should never be described as making rainwater safe merely because the water looks clear.
A dependable potable rainwater system requires:
Protection at the roof and gutters
Known and appropriate storage materials
Proper plumbing separation
Laboratory testing
Treatment matched to the contaminants
Validated disinfection
Safe installation
Routine maintenance
Repeated testing
Public drinking-water systems use multiple treatment and monitoring steps because no single cartridge addresses every possible hazard. A household rainwater system deserves the same layered approach, even when it operates on a much smaller scale.
