Do I Need to Drain Pool Below Return Jets? – A Complete Guide for Pool Owners

Maintaining a swimming pool involves various techniques and seasonal practices, and one of the most debated topics among pool owners is whether or not to drain the pool below the return jets. Understanding when, how, and why to lower water levels involves knowing your pool’s unique structure, climate considerations, and long-term maintenance goals.

This comprehensive guide explores the nuances behind draining pool water below return jets, helping you make informed decisions that preserve your pool’s longevity and performance.

Table of Contents

Understanding Pool Water Levels: What Are Return Jets?

Before delving into the specifics of draining below return jets, it’s essential to understand what these components are and their role in your pool system.

What Are Return Jets?

Also known as return inlets or eyeball fittings, return jets are the outlets located along the pool wall through which filtered water is returned to the pool. They help circulate and evenly distribute chemically balanced, filtered water throughout the pool to maintain cleanliness.

Return Jet Positions and Their Implication

Return jets are typically installed between 6 inches to 18 inches below the waterline, depending on the pool’s design. This positioning ensures optimal circulation without creating splashing or disturbing surface skimming activities.

Why Is Their Position Crucial When Draining?

Because of their placement, pool experts often refer to the return jets as a benchmark for water levels during certain maintenance or winterization procedures. Draining or lowering the water below this level alters the dynamics of pressure, cleanliness, and even temperature regulation in the pool structure.

When and Why You Might Need to Drain Below Return Jets

Deciding whether to drain your pool below return jets often comes down to a few key reasons:

1. Winterizing Your Pool

In areas with harsh winters, ice formation poses a significant risk to pool equipment and structure. Lowering the water level below the return jets helps prevent freeze damage.

By removing water from the plumbing lines, skimmer, and jets themselves, the risk of cracked pipes or dislodged fittings due to expansion is avoided. Pool owners are advised to lower the water level up to 6 inches below the lowest return jet, especially for in-ground pools.

2. Equipment Repair or Replacement

If you’re conducting maintenance, repairs, or upgrades to your return jets or plumbing system, draining the water level slightly below the jet inlets ensures:

Easier access to fixtures
No water interference during the removal or installation
Enhanced visibility and safety for technicians

3. Algae Infestation or Heavy Contamination

In cases of serious algae blooms or chemical imbalances, lowering the pool water to some extent may be necessary for:

Brushing the affected walls below the jet level
Avoiding continuous recirculation of contaminated water

However, in most filtration recovery tasks, only partial draining (not necessarily below the jets) is required unless instructed otherwise by a professional pool cleaning service.

When Draining Below Return Jets Is Not Recommended

Lowering the water too aggressively can lead to complications. Understanding when not to drain is just as important as knowing when you should.

1. For Regular Cleaning

Routine maintenance such as light vacuuming, filter cleaning, or periodic chemical balancing rarely requires altering the water level significantly. Draining even slightly below return jets during regular maintenance could:

Disrupt chemical levels
Affect circulation efficiency during re-fill
Increase evaporation loss and water usage unnecessarily

2. In Hot Climates or Dry Regions

In places where temperatures remain warm year-round, draining a pool below return jets can expose the pool walls to sun damage, staining, or corrosion. Exposed vinyl, fiberglass, or concrete surfaces can deteriorate, discolor, or crack when not submerged or covered.

3. Risk of Groundwater Uplift in In-Ground Pools

For in-ground concrete or fiberglass pools, emptying the pool entirely — even or especially below the return jets — can allow groundwater pressure from beneath to push the entire structure up out of the ground, especially after heavy rains.

Most pool professionals advise maintaining a minimum water level of at least halfway up the skimmer opening, which typically results in water sitting at or slightly above the return jets in many installations.

How to Safely Drain Pool Water Below the Return Jets (When Necessary)

If your situation demands lowering the water level, here’s how to do it effectively and safely.

Option 1: Use a Submersible Pump

The safest and most efficient way to lower the water level is using a submersible sump pump, which can be placed inside the deep end of the pool.

Submersible pumps allow you to precisely control the output
Avoid drain damage from heavy hoses or manual removal
Are faster and more energy-efficient than pool vacuum-based draining

Option 2: Using a Siphon Hose or Manual Techniques

For minor adjustments and when equipment like a pump is unavailable, a siphon hose can suffice — particularly in smaller pools or when only a slight drop is needed (e.g., an inch or two). However, this method is slower and less effective for full winterization.

Option 3: Pool Draining Attachments on Filter Systems

Some filtration systems (especially sand and DE filters) are equipped with filter drain lines that can be used to lower the water gradually. However, they are not ideal for lowering the level substantially — they are best for minor adjustments.

Draining Depth for Winterized Pools

As a general guideline:

Note: Always adhere to the manufacturer’s recommendations and consult with a local pool expert if you’re uncertain about the proper depth for your specific pool.

Important Considerations When Lowering Water Levels

Before undertaking the task of draining your pool below return jets — even temporarily — consider these factors.

Type of Pool and Construction

Vinyl pools can handle slight draining but should never be left completely empty.
Concrete or gunite pools are sturdy but must be empty only when hydrostatic pressure in the ground is low.
Fiberglass pools have strict guidelines and should never be emptied outside of repair situations.

Climate and Weather Conditions

In freezing climates, draining below return jets is often crucial, but it should be done before the first freeze.
In warmer climates, partial draining might not be necessary — especially if running the pump during the off-season.

Pool Cover Type

If draining is for winterization, solid winter covers can catch rain and snow. Water levels may need to be lowered further to prevent excessive weight at the end of the season.
Mesh covers allow water through, so lower water levels are less critical.

Hydrostatic Pressure from Groundwater

This is a primary concern for in-ground pools. Water in the pool helps balance the pressure from groundwater beneath. Removing too much water can cause the pool to “pop” out of the ground, resulting in costly structural damage.

Tools and Time Required for Pool Draining Below Return Jets

Essential Tools You’ll Need

Submersible pump or siphon hose
Extension hoses (if needed beyond pump length)
Water testing kit to re-balance after refilling
Plastic winterizing plugs
Winter pool cover (for seasonal draining)

Time Factors to Consider

Small to medium pools (15,000–20,000 gallons) may take 6–10 hours with a high-output pump.
Large pools (30,000+ gallons) may take over 10–14 hours even with dual pump setups.
Drainage time also depends on the outlet or destination (city sewer, yard, etc.).

Re-Filling Your Pool After Draining Below Return Jets

Reintroducing water after a seasonal drain or maintenance round should be handled carefully:

Steps to Refill Safely

Remove winter plugs and check the inlets for debris or damage.
Refill slowly to monitor for leaks or cracks that may have developed during drainage.
Test and rebalance water pH, alkalinity, and sanitizer levels.
Run the filtration system until water clarity is restored and levels remain stable.

Re-Maintenance Requirements

After refilling:

Clean the filter thoroughly
Brush the walls and vacuum the floor
Perform regular chemical testing to stabilize water within optimal range

Maintaining Proper Water Level in Pools Year-Round

Maintaining optimal water level helps your pool function efficiently and prevents undue wear and tear on filtration systems.

Water Level Guidelines for Different Seasons

Best Practices for Ongoing Water Level Maintenance

Keep an eye on evaporation and refill as needed
Test and maintain chemical balance to reduce scale buildup
Monitor heavy rains that raise the water level unexpectedly
Consider a water leveler or automatic fill device if fluctuations are frequent

Expert Tips for Pool Owners

Whether you’re a first-time owner or seasoned in pool care, knowing how much to drain and when is essential. Here are real-world insights from professional technicians and pool builders.

Customized Advice for Local Climates

Pool professionals often issue region-specific directives. For instance, a homeowner in northern Illinois may require significantly more draining than someone in central Texas where freezing is rare.

Hydrostatic Valve for Concrete Pools

Concrete pools are increasingly being installed with hydrostatic valves, which help equalize pressure and reduce the need to completely drain or risk pool damage during winter.

Analogue vs Smart Pool Systems

Modern smart pool systems can include sensors that notify owners about drastic water level changes or pressure issues, potentially preventing over-draining or under-draining.

Conclusion: Do I Need to Drain Pool Below Return Jets?

When addressing the question “Do I need to drain the pool below return jets?”, the answer is not a universal yes or no; it depends on multiple interlinked factors such as:

Your pool type
Climate and location
Maintenance purpose
Groundwater risks
Seasonal procedures

Draining below return jets is necessary during winterization, for repairs, and in areas with heavy freezes. However, for everyday or off-season care, it’s generally better to maintain water levels that ensure cleanliness, equipment longevity, and structural stability.

If in doubt, always consult a certified pool technician. Proper drainage can protect your pool from damage and save you from costly repairs in the future.

Why would I need to drain my pool below the return jets?

Draining a pool below the return jets is sometimes necessary during specific maintenance or repair tasks, such as cleaning the lines, replacing underwater lights, or winterizing the pool. When working on the filtration system or inspecting the pipes connected to the jets, it’s crucial to lower the water level to allow for safe and effective access. In regions where freezing temperatures are a concern, lowering the water level can prevent ice damage to the return jets and associated plumbing.

However, it’s important not to drain the pool excessively, as keeping some water in the pool helps maintain the structural integrity of the shell. Completely draining a pool can cause issues such as cracking in concrete or vinyl liners, especially if the pool was not designed to be empty for long periods. The general rule is to drain the water just below the return jet openings unless otherwise specified by a professional or local climate conditions require more significant adjustments.

Can I leave the return jets submerged after draining some of the water?

It’s best to drain the water just below the return jets rather than leaving them submerged during certain maintenance tasks, especially during winterization. If the water level remains above the returns, trapped water in the jet lines may freeze, leading to cracks or blockages that can be expensive to repair. Lowering the water beneath the jets allows this water to be properly blown out or drained from the system to prevent freeze damage.

However, during routine maintenance like cleaning or inspecting the jets, it may not be necessary to drain below them. In these cases, simply lowering the water level enough to access the area without exposing the jets can suffice. Always check with a pool professional if you’re unsure whether to drain below the jets for a particular task to avoid damaging your pool system.

What tools do I need to drain my pool below the return jets?

To drain your pool below the return jets, you’ll typically need a submersible pump, a garden hose long enough to reach a drainage area, and possibly a wet vacuum for smaller pools. The pump is used to efficiently remove water from the pool, while the hose directs the water away from the pool area to prevent flooding. A wet vacuum can come in handy for pools with awkward shapes or limited access.

Additional tools may include a screwdriver or wrench if you need to disconnect pipes or clean the jet fittings manually. For larger pools, especially in colder climates, a leaf blower or air compressor may be used to clear water from the lines after draining. Always ensure you have the proper tools before starting the process, and follow all safety guidelines when handling electrical devices near water.

Is it safe to drain a concrete pool completely?

Draining a concrete pool completely is generally not recommended unless the pool was specifically designed for that. Most concrete pools rely on water pressure from the inside to counterbalance the pressure from the surrounding soil and groundwater. If the pool is fully drained without proper hydrostatic relief or in areas with high groundwater levels, it can lead to lifting or structural damage.

In most cases, draining just below the return jets is sufficient for routine maintenance or winterization. If more extensive draining is required—such as for resurfacing or major repairs—consult a professional pool contractor who can take the necessary precautions. They may install hydrostatic relief valves, monitor groundwater levels, or use support structures to prevent damage during the draining process.

How can I prevent damage to return jets during the draining process?

To prevent damage to the return jets when draining your pool, ensure you only lower the water level to the point just below the jet openings. Going lower than necessary increases the risk of accidentally hitting or dislodging the jets during maintenance. Additionally, never use the pool’s main drain as a method to empty the pool, as this can create a vacuum effect and damage the plumbing system.

After draining, inspect the return jets for debris or wear. If you’re winterizing the pool, use jet covers or air bladders to prevent water from re-entering the lines and freezing. For long-term periods when the pool is not in use, consider installing protective plugs in the jets to maintain their integrity and keep out insects and debris. Taking these precautions prolongs the life of your return jets and prevents costly repairs in the future.

Should I drain the pool below return jets if I’m closing it for winter?

In cold climates where freezing is a concern, it’s typically recommended to drain the pool water below the return jets when winterizing to prevent ice from forming inside the plumbing lines. Water trapped in these lines can expand when frozen, leading to cracked piping or damaged fittings. This step is crucial to protect your pool system during the off-season and avoid expensive repairs in spring.

However, pool type and local climate play a significant role in how much you should drain. For example, above-ground pools or certain in-ground pools may have different guidelines. Always follow manufacturer recommendations or consult with a professional pool service to determine the correct water level for winter closure. If you’re using a winter cover, make sure you leave enough water to support it without compromising the structural health of the pool.

What should I do after draining the pool below the return jets?

After draining your pool below the return jets, the next step is typically to clean or winterize the system. This involves blowing out the plumbing lines with an air compressor to remove any leftover water, then inserting expandable plugs or air bladders to prevent refilling. If you’re preparing for winter, install a proper pool cover and ensure that the skimmer area is also protected with a cover or float to absorb ice pressure.

If drainage is part of maintenance rather than winterization, inspect and clean the return jets before refilling the pool. Look for any signs of corrosion, blockage, or wear. Refill only after all maintenance tasks are complete, ensuring the chemical balance is restored before resuming normal operation. Taking these steps protects your investment and ensures the pool remains in good condition for future use.