Product Overview

The Pentair T40BW AutoFill Automatic Water Leveler is designed to automatically maintain the proper water level in a swimming pool or spa, reducing the need for manual filling and helping prevent problems caused by excessively low or high water levels.

This model features a side-mounted float valve and a white lid and top ring, making it ideal for installation in light-colored pool decks and surrounding surfaces. Pentair identifies T40BW specifically as the white AutoFill configuration with a side-mounted float valve.

The mechanical float-valve design operates without electronic controls, providing a simple and dependable solution for maintaining water level in standard inground pools.

How the Pentair AutoFill Works

Normal evaporation, splash-out, backwashing and everyday pool use continually lower the water level.

The T40BW automatically responds to a dropping water level through its mechanical float-valve assembly. When the water drops below the preset level, the valve allows fresh water into the system. Once the desired level is reached, the float closes the water supply.

This helps maintain a more consistent pool level without requiring the homeowner to repeatedly add water with a garden hose.

Key Features

Genuine Pentair OEM AutoFill

Manufacturer Part Number: T40BW

Automatic pool water-level control

Side-mounted float valve

White lid and top ring

Mechanical operation — no electronic controls

Helps maintain proper operating water level

Helps protect pool equipment from low-water conditions

Helps reduce accidental pool overfilling

Helps minimize water waste

Compact installation footprint

Durable ABS polymer construction

Corrosion and chemical resistant

Ideal for new construction and pool remodeling

Replacement components available separately

Pentair describes its automatic water fillers as using durable ABS polymer construction with a compact approximately 7-inch-diameter design.

Benefits

Why Proper Pool Water Level Matters

Maintaining the correct pool water level is important for proper circulation.

If the water becomes too low:

• The skimmer can begin drawing air
• The pump may lose prime
• Circulation can become inconsistent
• Pump components can potentially be damaged

Pentair specifically promotes its AutoFill systems as helping prevent equipment damage associated with low water levels.

An automatic water leveler can also help prevent excessive filling that may waste water or damage surrounding landscaping.

Compact In-Deck Design

Pentair's AutoFill system uses a compact round housing designed for integration into the pool deck.

Once installed, only the top lid is prominently visible, helping keep the pool area clean and unobtrusive.

The white T40BW lid works particularly well with:

• White concrete
• Light-colored decking
• Light pavers
• Quartz finishes
• Contemporary pool decks

Specifications

Replacement Parts Available

Common Pentair replacement components for this AutoFill family include:

Pentair continues to list replacement lids, rings and valve components for the automatic water-filler family.

Warranty & Compatibility

Side-Mounted Float Valve

The T40BW differs from Pentair T40FW.

T40BW uses a side-mounted float valve.

T40FW uses a Fluidmaster® valve.

If replacing an existing automatic filler, verify the valve style before ordering. Pentair currently lists both configurations as separate models.

Plumbing Connections

Pentair's automatic water-filler assembly incorporates plumbing connections for the water supply, equalizer and overflow functions depending on installation configuration.

Pentair documentation identifies connections including:

• 3/4" slip supply connection
• 1-1/2" slip equalizer connection
• 3/4" slip overflow connection

Exact plumbing requirements should be confirmed against the Pentair installation instructions before construction.

Customer-Facing Q&A

Q: What is Pentair T40BW?
A: T40BW is the white Pentair AutoFill automatic water leveler equipped with a side-mounted float valve.

Q: Does T40BW automatically add water to the pool?
A: Yes. Once properly installed and connected to a water supply, the mechanical float valve automatically allows water into the pool system when the level drops.

Q: Is T40BW electronic?
A: No. Pentair's automatic water-level control operates mechanically and does not require electronic controls.

Q: What color is T40BW?
A: White.

Q: What's the difference between T40BW and T40FW?
A: The primary difference is the valve: T40BW: Side-mounted float valve; T40FW: Fluidmaster® valve. Both are available with a white lid.

Q: Can it help prevent pump damage?
A: Maintaining proper water level helps prevent the skimmer from drawing air and can help protect circulation equipment from low-water conditions. Pentair specifically identifies equipment protection as one of the benefits of the AutoFill system.

Q: Can I replace the white lid separately?
A: Yes. The replacement white AutoFill lid with screws is Pentair T10W.

Q: Is the white top ring replaceable?
A: Yes. The replacement white top ring is Pentair T16W.