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For most home rainwater tanks and cisterns, Grundfos is one of the strongest submersible-pump brands to consider. Its SB and SBA lines are made for clean-water supply, rainwater harvesting, and pressure boosting. Franklin Electric is another strong choice, especially when the job involves a larger cistern, higher pressure, or a well-style installation.
The brand matters, but the pump must also match the tank, pipe size, lift, pressure needs, and expected water flow. A well-known pump that is the wrong size can still give poor pressure, cycle too often, or fail early.
Best Brand for a Rainwater Tank
For a typical residential rainwater system, Grundfos is a good first brand to check.
The Grundfos SB and SBA are submersible pressure pumps designed to sit inside a tank or cistern. Grundfos lists rainwater harvesting, garden irrigation, and household water pressure boosting among their intended uses. The pumps are designed for clean water rather than water carrying large solids.
The SBA is especially useful when you want a simpler setup because its controller is built into the pump. It can start when water is needed and stop when demand ends. It also includes dry-running protection. The SB normally works with an external controller.
A floating inlet option can also be useful in rainwater tanks. Instead of pulling water directly from the very bottom of the tank, it draws from closer to the surface. This can reduce the amount of settled sediment reaching the pump.
Other Submersible Pump Brands Worth Considering
Different brands make more sense for different jobs.
| Brand | Good fit for | Main reason to consider it |
|---|---|---|
| Grundfos | Rainwater tanks, cisterns, garden supply, household reuse | Dedicated submersible pressure pumps for rainwater systems |
| Franklin Electric | Cisterns, larger water systems, wells | Wide range of cistern and well pumps |
| Goulds Water Technology | Wells and residential pressure systems | Large range of multistage submersible water pumps |
Franklin Electric
Franklin Electric is a strong alternative when you need a pump specifically designed around a cistern or a more traditional water-supply system.
Its C1 cistern pump, for example, is intended for tanks and cisterns and is listed for water-reclamation uses including rain catchment basins. Franklin Electric also makes a much wider range of submersible well pumps when greater lift or flow is required.
That makes Franklin Electric worth considering for systems where a small all-in-one rainwater booster does not provide enough performance.
Goulds Water Technology
Goulds Water Technology, a Xylem brand, is another established option for residential water systems.
Its submersible range is especially relevant to well-style installations. These pumps use multiple impeller stages to create the pressure needed to move water through longer pipes or raise it from greater depths. Xylem also recommends professional installation for its residential water and wastewater equipment.
For a simple backyard rainwater tank, that type of pump may be more than you need.
Choose the Pump Before You Choose the Brand
Start with the job the pump must do.
A pump supplying one garden hose has very different requirements from a pump supplying toilets, irrigation zones, and an outdoor faucet at the same time.
Check these factors before choosing a model.
Required Flow Rate
Flow rate is how much water the pump can move during a certain amount of time. It is commonly shown in gallons per minute or liters per minute.
Estimate the amount of water that may be used at the same time.
A single hose may have modest demand. Several sprinklers running together can require much more flow.
Do not choose a pump only because it has a large maximum-flow number. Maximum flow is usually measured under conditions with little resistance. Actual flow drops as the pump has to produce more pressure.
Head Height
Head height describes how hard the pump must work to move water through the system.
It includes more than the vertical distance between the tank and the outlet. The pump must also overcome:
- Vertical lift
- Pipe friction
- Filters
- Valves and fittings
- Irrigation equipment
- Required outlet pressure
For example, a pump may need to lift water only 10 feet, but a long narrow pipe and several filters can add considerable resistance.
Compare your required flow at the required head with the manufacturer's pump curve rather than looking only at maximum flow or maximum head.
Check the Outlet Connection
Make sure the pump can connect sensibly to your existing plumbing.
Check:
- Pump discharge size
- Pipe diameter
- Thread type
- Check-valve requirements
- Hose or pipe adapters
- Pressure controller connections
Avoid reducing a large pump outlet immediately into very small pipe unless the system was designed that way. Small pipe increases friction and can reduce useful flow.
Look for Dry-Run Protection
Dry running happens when a pump continues operating after the tank runs out of water.
Water normally helps cool and lubricate parts of a submersible pump. Running without enough water can damage some pumps.
For a rainwater tank, look for either built-in dry-run protection or a suitable float switch that stops the pump before the water level gets too low.
Some Grundfos SB/SBA configurations include low-water and dry-running protection features.
Do not assume every submersible pump has this protection.
Consider a Floating Intake
With comparing reputable water-pump manufacturers, you can compare the system’s suction conditions and dry-run protection.
Rainwater tanks often collect small amounts of sediment even when gutters and inlet screens are maintained.
A pump sitting near the bottom can draw some of this material toward its intake.
A floating intake pulls water from below the surface instead. This usually keeps the intake away from both floating debris and settled material at the tank bottom.
Grundfos offers SB/SBA versions using a flexible hose and floating inlet strainer for this purpose.
A floating intake does not replace normal tank cleaning or inlet filtration.
Don't Oversize the Pump
Buying a larger pump does not automatically improve a rainwater system.
An oversized pump can create:
- Excessive pressure
- Fast cycling
- More stress on fittings
- Unnecessary electrical load
- Problems with irrigation components
- Higher flow than filters can handle
Choose a pump that provides the required flow while operating comfortably within its normal performance range.
If you need steady household pressure at several fixtures, the control system can be just as important as the pump itself.
Submersible Pump or Surface Pump?
A submersible pump sits underwater inside the tank.
This has several advantages.
It does not need to pull water through a long suction pipe, and the surrounding water helps reduce pump noise. Grundfos specifically recommends its SB and SBA submersible pumps for rainwater tanks where one or two outlets may be used at a time.
A surface-mounted pump can still be the better choice when easy servicing is important or the tank design does not provide a suitable location for a submerged pump.
Neither design is automatically better.
What About Drinking-Water Systems?
Choosing a pump approved or designed for drinking-water applications does not make collected rainwater safe to drink.
Roof runoff can contain microorganisms, animal waste, dust, roofing contaminants, and other material.
A drinking-water rainwater system needs to be treated as a complete system. That can include suitable collection surfaces, debris control, first-flush management, storage, filtration, disinfection, current laboratory testing, maintenance, and compliance with applicable local requirements.
Potable means water intended to be safe for drinking. Non-potable water is water that is not intended for drinking.
If rainwater will enter household potable plumbing or be used for drinking, get qualified local guidance rather than relying on the pump or a single filter to establish water safety.
Which Brand Should You Pick?
For a normal residential rainwater tank, start by looking at Grundfos, particularly the SB or SBA range. The pumps are specifically designed around clean-water tanks, cisterns, irrigation, and rainwater reuse.
Consider Franklin Electric when you need a cistern pump with different flow or pressure requirements, or when the installation is closer to a traditional well-water system.
Consider Goulds Water Technology for deeper or more demanding residential water-supply installations where a well-style multistage submersible pump makes sense.
Whichever brand you choose, size the pump using the required flow and head, not horsepower or brand name alone.
Frequently Asked Questions
Is Grundfos a good brand for a rainwater tank?
Yes. Grundfos makes SB and SBA submersible pumps specifically suited to rainwater tanks, cisterns, irrigation, and domestic water pressure boosting. The SBA also has an integrated controller for automatic operation.
Is Franklin Electric a good submersible pump brand?
Yes. Franklin Electric makes both cistern pumps and a broad range of submersible well pumps. Its C1 line is specifically intended for tanks and cisterns and includes rain-catchment applications.
How many horsepower should a rainwater pump have?
There is no single correct horsepower. Size the pump according to required flow, total head, pipe resistance, and required outlet pressure. Two pumps with the same horsepower can have very different performance.
Should a rainwater pump have a float switch?
A float switch is useful because it can stop the pump when the water level becomes too low. This helps protect the pump from dry running. Some pumps have built-in protection, while others require a separate float or controller.
Is a floating intake better for a rainwater tank?
It can be. A floating intake draws water away from sediment settled on the tank floor. It can help reduce the amount of debris reaching the pump, but it does not replace screens, prefiltration, or tank maintenance.
Can I use a sump pump in a rainwater tank?
A sump pump may move water, but it is often designed for drainage rather than supplying steady pressure to hoses, irrigation equipment, or household fixtures. A clean-water pressure pump is usually a better match when usable pressure is required.
Can a submersible pump make rainwater safe to drink?
No. A pump only moves water. Drinking-water safety depends on the complete collection, treatment, testing, storage, plumbing, and maintenance system.
