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Connecting a water tank to your house usually means adding a pump, pressure control, suitable pipework, and a safe way to keep tank water separate from any public drinking-water supply. The exact setup depends on what the water will be used for.
For rainwater, the simplest house connection is usually a separate non-potable system serving approved uses such as toilets, laundry, or outdoor taps where local rules allow them. Supplying drinking taps, showers, or the whole house requires a much more careful treatment and testing plan.
A basic pumped system often follows this path:
Water tank → shutoff valve → pump → pressure control → treatment as needed → house plumbing
Do not simply join a rainwater tank pipe to the same pipe that carries municipal drinking water. That can create a cross-connection and allow untreated water to flow backward into the drinking-water system. The U.S. EPA identifies cross-connections and backflow as important drinking-water contamination risks.
Decide What the Tank Water Will Supply
Start with the intended use. It determines almost everything that comes next.
Outdoor use only
If the tank only supplies garden hoses or irrigation, the system may be fairly simple. You may need:
- A tank outlet and shutoff valve
- A pump if gravity does not provide enough pressure
- A sediment screen or filter appropriate for the irrigation equipment
- Pipe or hose rated for the expected pressure
- Freeze protection where needed
This type of system normally stays completely separate from household drinking-water plumbing.
Toilets, laundry, or other indoor non-potable uses
Indoor rainwater reuse needs dedicated plumbing. Non-potable means water that is not intended or established as safe for drinking.
The rainwater pipes should remain separate from drinking-water pipes and be identified as required by local rules. Any municipal-water backup arrangement also needs approved cross-connection protection.
Drinking and whole-house use
Connecting collected rainwater to every fixture is a different level of project.
Rainwater is not automatically safe to drink because it looks clear. Roof runoff can contain germs, animal waste, dust, metals, chemicals, and contaminants from roofing, gutters, pipes, and storage materials. CDC recommends regular testing for germs and chemicals when rainwater is used for drinking, cooking, or bathing.
A potable system—meaning a system supplying water intended to be safe for drinking—may require suitable collection materials, protected storage, prefiltration, water treatment chosen for the contaminants present, disinfection, current laboratory testing, and ongoing maintenance. One sediment filter, carbon filter, UV unit, or other single device should not be treated as proof that roof runoff is safe to drink. Different treatment methods address different contaminants.
For a whole-house potable rainwater system, involve your local health authority and a qualified water-treatment or plumbing professional.
A Typical Water Tank-to-House Layout
A pumped system may look like this:
Tank → tank outlet → isolation valve → pump → pressure tank or pump controller → filters/treatment → house distribution pipe
The exact order can change with the pump and treatment equipment.
1. Tank outlet
Use a proper tank outlet rather than drilling a hole and trying to seal a pipe directly through the wall.
Many tanks use a molded threaded outlet. Others use a bulkhead fitting, which is a fitting designed to make a sealed pipe connection through the wall of a tank.
Include a shutoff valve close to the tank. This lets you isolate the tank when servicing the pump, filter, or downstream plumbing.
A union or another removable connection can also make future pump and valve maintenance easier.
2. Pump
Most ground-level tanks need a pump to provide useful household pressure.
The right pump depends mainly on:
- Required flow rate
- Required pressure
- Vertical lift
- Distance to the house
- Pipe size
- Pressure loss through pipes and treatment equipment
- Whether the pump is above or below the tank water level
Flow rate is how much water the pump can deliver over time, usually measured in gallons per minute or liters per minute.
Head height describes the resistance the pump must overcome, including vertical lift and pressure requirements. About 2.31 feet of water head equals 1 psi, so producing normal household pressure requires much more pump head than simply lifting water a few feet.
Do not choose a pump based only on tank size. A 5,000-gallon tank does not necessarily need a larger pump than a 1,000-gallon tank. The pump needs to match the plumbing demand and total head.
3. Suction plumbing
If an above-ground pump pulls water from the tank, keep the suction pipe reasonably short, correctly sized, and airtight.
Small leaks on the suction side may pull air into the pipe without leaking much water outward. This can cause:
- Loss of prime
- Poor flow
- Pump cycling
- Noise
- Difficulty building pressure
Some surface pumps require a flooded inlet, while self-priming pumps can tolerate certain suction arrangements. Follow the pump manufacturer's limits for suction lift and pipe size.
An underground cistern may instead use a suitable submersible pump inside the tank.
4. Pump protection
A pump should not continue running when the tank is empty.
Dry running can damage many pumps. Depending on the system, protection may come from:
- A tank level switch
- A float switch
- A pump controller with dry-run protection
- Another manufacturer-approved control
Low-water protection becomes especially important when tank levels change greatly between rainy and dry periods.
How to Create Steady Household Pressure
A pump cannot simply be connected to a pipe and expected to behave like a municipal water supply.
You need a way to control it.
Pressure tank and pressure switch
A traditional setup uses a small pressurized storage tank plus a pressure switch.
The pressure tank stores a limited amount of pressurized water. The pump starts when pressure falls to a set point and stops once pressure rises to the upper set point.
This reduces very short pump cycles every time somebody briefly opens a tap.
Electronic pump controller
Some systems use an electronic controller that starts the pump when it senses water demand and stops it when demand ends.
The correct arrangement depends on the pump. Do not mix controllers, pressure tanks, switches, and pumps without checking their operating requirements.
Constant-pressure system
Larger or more complex installations may use variable-speed controls to maintain more consistent pressure as demand changes.
These systems can work well but add electrical and control complexity. Installation and troubleshooting may be better handled by a pump professional.
Check Your Required Flow Before Choosing a Pump
Think about which fixtures might operate at the same time.
A tank supplying one outdoor hose has a much smaller flow requirement than a tank supplying:
- A shower
- A toilet filling
- A washing machine
- A sink
all at once.
The pump must provide sufficient flow at the pressure you need. A pump's maximum advertised flow at very low head does not tell you what it will deliver once it has to overcome elevation, household pressure, pipe friction, and filters.
Use the pump performance curve to check its expected flow at your calculated system head.
Pipe Size Matters
A pipe can be large enough to physically connect to the pump but still be too small for the required flow.
Long, narrow pipes create more friction loss. This reduces the pressure available at the house.
This matters especially when:
- The tank is far from the house
- The house is uphill from the tank
- Several fixtures may run together
- Filters or treatment equipment add resistance
Avoid reducing the pump's inlet pipe below the manufacturer's requirements.
Your final pipe diameter should be based on flow, distance, elevation, pump requirements, and applicable plumbing rules rather than simply matching whatever fitting happens to be on the tank.
Do You Need Filters Before the House?
Usually, some form of debris management is useful in a rainwater system, but the treatment needed depends on the water's intended use.
Good water quality starts before the tank.
Planning around a pump suited to tank-to-house delivery helps verify pump-pressure symptoms and possible loss of prime.
A rainwater collection system may include:
Roof → gutter screen → first-flush or other debris control → tank inlet screening → storage tank → pump → treatment → intended use
A first flush device diverts some of the early runoff from a rain event. Early runoff can carry accumulated dirt and contaminants from the roof. A first-flush device can reduce this load, but it does not make the remaining water potable.
Sediment filtration
A sediment filter removes particles.
Its micron rating describes the approximate size of particles the filter is designed to capture. A smaller micron number generally means finer filtration, but finer filtration can also clog faster and create more pressure loss.
Sediment filtration can help protect pumps, valves, appliances, irrigation emitters, and later treatment stages. It does not establish that the water is microbiologically or chemically safe.
Additional treatment
Depending on the intended use and actual water quality, a system might require additional filtration or treatment.
For drinking-water applications, treatment needs should be based on water testing and the contaminants that must be controlled. CDC notes that different treatment technologies remove different germs and chemicals and recommends choosing treatment for the contaminants actually present.
Keep Municipal Water and Tank Water Safely Separated
This is one of the most important parts of connecting a tank to a house.
Imagine your house normally receives municipal drinking water but you want rainwater to supply toilets. It may seem convenient to connect both sources to the same pipe and switch between them with valves.
That arrangement can create a cross-connection.
Backflow means water flows in the wrong direction. If pressure conditions change, non-potable tank water could potentially move toward the potable water system. EPA guidance treats connections between potable and non-potable systems as contamination risks that need proper cross-connection control.
A simple check valve should not automatically be assumed to provide the protection required by your local authority.
Depending on local requirements, a backup water arrangement may require:
- A physical air gap
- An approved backflow prevention assembly
- Separate break tank or day tank
- Dedicated dual plumbing
- Inspection or testing by an approved professional
An air gap creates a physical open space between the potable supply outlet and the receiving water level so contaminated water cannot simply flow backward through the supply pipe.
EPA rainwater guidance notes that requirements for municipal backup connections and backflow protection vary by jurisdiction.
Can You Use Gravity Instead of a Pump?
Sometimes.
Water pressure increases as the tank water level rises above the fixture. However, a tank sitting a few feet above ground provides only modest pressure.
Every 2.31 feet of vertical water height produces about 1 psi before friction losses.
For example, 10 feet of vertical difference provides only about 4.3 psi under ideal static conditions. Pressure will be lower at a flowing fixture because the pipe, fittings, valves, and filters create resistance.
Gravity can be useful for:
- Drip irrigation
- Low-pressure garden watering
- Filling containers
- Special fixtures designed for low pressure
It is usually less suitable for conventional household plumbing unless the storage tank is substantially higher than the fixtures and the system has been designed around gravity pressure.
Do not place a large water tank on an elevated platform without a structural design appropriate for the full load. Water is heavy, and tank platforms need to handle the filled tank plus environmental and structural loads.
What If the House Is Higher Than the Tank?
Elevation must be included when sizing the pump.
If the house connection is 30 feet above the tank water level, the pump must first overcome roughly 30 feet of elevation head before providing useful pressure at the house.
You must then add:
- Desired fixture pressure
- Pipe friction
- Filter losses
- Valve and fitting losses
- Any additional elevation inside the house
This combined requirement is often called total dynamic head.
A pump that works well next to a tank on level ground may provide disappointing pressure when pushing water uphill through a long pipe.
Protect the Tank From Contamination
House plumbing cannot compensate for a poorly maintained storage tank.
For rainwater storage, practical measures include:
- Keeping tank openings securely covered
- Screening appropriate vents and inlets against insects and debris
- Preventing surface runoff from entering the tank
- Keeping gutters and collection surfaces maintained
- Removing accumulated sediment when necessary
- Keeping animals and pests from accessing openings
- Inspecting fittings, covers, overflow screens, and pipes
- Protecting stored water from avoidable contamination during maintenance
CDC notes that roof materials, gutters, piping, animal waste, dust, and storage materials can all affect collected rainwater quality.
Plan the Overflow Before Connecting the House
The tank still needs a safe overflow even though water is being pumped into the house.
The overflow should handle incoming water when the tank becomes full and direct it somewhere appropriate without damaging:
- The tank foundation
- The house foundation
- Nearby structures
- Slopes
- Septic areas
- Neighboring property
Do not reduce or block the designed overflow simply because normal household use removes water from the tank.
Protect the System From Freezing
In freezing climates, exposed tank plumbing, pumps, filters, and small pipes are vulnerable.
Consider the entire water path:
- Tank outlet
- Valves
- Pump
- Pressure tank
- Filters
- Above-ground pipes
- Exterior faucets
Some systems are drained and shut down seasonally. Others require appropriately designed frost-protected installation.
Insulation alone does not guarantee that a water-filled pipe or filter will not freeze.
Do Not Forget Electrical Safety
House-pressure pumps often use mains electricity and may operate around wet equipment.
The installation may require appropriate:
- Circuit protection
- Grounding
- Disconnects
- Outdoor or wet-location equipment
- Cable protection
- Controls
Electrical requirements depend on the pump and local electrical rules. Have permanent mains-voltage wiring performed or checked by a qualified electrician where required.
A Practical Installation Sequence
For a typical non-potable rainwater connection, the project can be planned in this order:
- Choose the intended fixtures. Decide exactly where tank water will be used.
- Check local requirements. Confirm whether the intended indoor use is permitted and what cross-connection protection is required.
- Estimate peak water demand. Determine how much flow may be needed at one time.
- Calculate the pump's head requirement. Include elevation, desired pressure, pipe friction, and treatment losses.
- Choose suitable pipe sizes. Avoid excessive friction and follow pump inlet requirements.
- Install a proper tank outlet and isolation valve.
- Install the pump and dry-run protection.
- Install pressure controls. Use the arrangement specified for the chosen pump.
- Add filtration or treatment appropriate for the intended use.
- Run dedicated plumbing to the approved fixtures.
- Provide required backflow or physical separation from potable water.
- Test the system for leaks, correct pump cycling, pressure, flow, and proper source separation.
- Create a maintenance schedule. Include tank inspection, screens, filters, pump controls, treatment equipment, and any required backflow-device testing.
When to Call a Professional
Connecting a tank to a simple garden line can often be a reasonable DIY project.
Get qualified help when the system involves:
- Indoor household plumbing
- Municipal-water backup
- Potable and non-potable piping in the same building
- Drinking-water treatment
- Large pressure pumps
- Complex pump controls
- Permanent electrical wiring
- Underground cistern entry
- Structural tank supports
- Plumbing permits or inspections
- Backflow prevention assemblies requiring certification or testing
As of August 2026, rainwater reuse and plumbing requirements in the United States can differ by state and local jurisdiction. Check with your local plumbing or building authority, health department, and water utility before making an indoor connection. EPA guidance also recommends using backflow devices approved by the relevant state or local authority and following local installation and testing requirements.
Frequently Asked Questions
Can I connect a water tank directly to my house plumbing?
You can supply house plumbing from a tank, but most ground-level systems need a pump and pressure controls. Rainwater or other non-potable water must also be kept safely separated from any potable public water supply.
Do I need a pump between my water tank and house?
Usually, if the tank is near ground level. A pump provides the pressure needed by normal fixtures. A sufficiently elevated tank can sometimes provide gravity pressure, but a small height difference produces only low pressure.
What size pump do I need for a water tank?
Choose the pump according to required flow and total dynamic head, not tank capacity alone. Account for elevation, desired house pressure, pipe friction, filters, treatment equipment, and the number of fixtures that may operate together.
Where should the filter go, before or after the pump?
It depends on the pump and filter. Coarse debris control may be used before the pump if the pump manufacturer allows it, while finer filtration is commonly placed on the pressurized side. Do not install a restrictive filter on a pump inlet unless the pump and filter arrangement is designed for it.
Can rainwater and municipal water use the same house pipes?
Do not directly connect the two sources unless the arrangement has been specifically designed and approved for cross-connection protection. Dedicated non-potable plumbing or a properly designed air-gap backup system is often safer and may be required locally.
Can I use tank water for drinking?
Tank water should not be assumed safe to drink. For collected rainwater, drinking use requires attention to the entire collection, storage, treatment, testing, and maintenance system. CDC recommends regular testing for germs and chemicals when rainwater is used for drinking, cooking, or bathing.
How often should I maintain a tank-to-house system?
There is no single interval that fits every component. Regularly inspect collection screens, the tank, pump, valves, filters, pressure controls, overflow, and treatment equipment, and follow manufacturer schedules. Drinking-water systems also need appropriate ongoing water testing and any inspections required by local authorities.
