Tri-Valley Pool Owners: How to Maintain the Perfect Water Level In Your Pool
- Sage Leif
- May 11
- 9 min read
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The Tri-Valley’s (Pleasanton, Livermore, Dublin, San Ramon, & Danville) sunny, dry climate = pool water loss. Keeping your swimming pool properly filled is essential for the health of your pool and equipment.
What is the proper water level?
“If the water is too high, that’s bad, too low, that’s even worse!”
- Frustrated Pool Owner
The proper water level is halfway up the skimmer opening. Higher than the skimmer, and the pump won’t be able to skim debris, lower than the skimmer opening, and the pump could run dry.
Why is my pool losing water?
“I am constantly having to add water to my pool!”
- Random Pool Owner
Your pool will lose water in different ways:
Evaporation
The most common cause of water loss, especially in hot, dry climates like Tri-Valley, CA.
Accelerated in pools without a cover by high temperatures, low humidity, afternoon winds, and heated water. In other words, our Tri-Valley climate has primed your pool for evaporation.
Typical loss: 1–2 inches per week in summer.
Splash-out
Water splashing out from swimmers, playing, cannonballs, etc.
Over time, this can add up, especially in frequently used pools.
Backwashing & Waste Cycles
When cleaning sand or DE filters, you intentionally send water out of the system.
Also includes “vacuum to waste” or lowering the water level during storms or chemical issues.
Leaks in Equipment or Plumbing
Leaks can occur in pipes, valves, pump seals, filter housings, heaters, or underground.
Sometimes small and hard to spot, especially if hidden underground. Even a small leak can result in significant water loss over time. For example, one drip per second can result in at least 2 gallons of water loss per pump cycle (usually 8 hours). Many older systems have a few leaks like this here and there.
Keep In Mind: Your Autofill Might Be Masking a Leak
Autofills add water automatically, which can hide leaks by keeping the level steady.
A good clue: rising water bills or constant autofill activity.
Is it a leak or is it evaporation?
“I think my pool might have a leak, I am losing 1-2 inches of water a week!”
- Concerned Pool Owner
Before you panic… good news: 1–2 inches of water loss per week is usually normal due to evaporation, especially in warm, dry climates like the Tri-Valley area.
However, if you are still concerned about a possible leak, you may want to consider doing a basic meter flow check. Many leaks associated with the pool are found in the pool equipment. Try looking for visible leaks when the pool equipment is on. Keep an eye out for white crusty mineral deposits on pipes, which could indicate a slow leak. Also, look for wet spots on the ground around the pool, pool equipment, and between the equipment and the pool. Pool equipment can leak even when off.
Still not sure? Before you spend hundreds of dollars on leak detection, try a bucket test!
Bucket Test Steps:
Fill a bucket with pool water and place it on a pool step.
Mark the water level inside the bucket and the pool’s water level outside the bucket. Ensuring the water level inside the bucket and outside is the same.
Wait 24–48 hours.
Check if the pool water level drops significantly more than the bucket water level; if so, you have a leak. If not, water loss is due to evaporation.
How many gallons are in an inch of water?
“1-2 inches of water a week isn't that much, right?”
- Random Pool Owner
When your pool water drops an inch, how much water is that in real terms? It’s more than you might think. One inch of water over the surface of a pool represents a large volume. The exact number of gallons depends on your pool’s size (surface area).
Most pools in our area have a surface area of around 800 sq ft. So if you lose 1 inch per week to evaporation, that equals about 500 gallons! For reference, the average family of four uses around 2800 gallons of water weekly (bathroom, kitchen, garden, etc).
So, in practical terms, “losing one inch” sounds small, but it could mean hundreds of gallons that need replacing. Over an entire summer, these losses add up to many thousands of gallons. This is why monitoring your pool’s water level is so important, especially during our dry season.
Why is a pool with low water level so dangerous?
“Water is too expensive! I’m not going to fill the pool this week.”
- Shortsighted Pool Owner
Low water levels in a pool can cause serious problems, both for the equipment and the quality of the water. Here are the main cons and risks:
❌ 1. Damage to the Pool Pump
The pump needs a steady supply of water to avoid running dry. If the water drops too low, air can get sucked into the lines and pump. This will cause the pump to:
Lose prime (stop circulating water)
Cavitate (air bubbles causing vibration) which erodes internal parts and causes noisy operation and wear in pumps and valves
Overheat
Burn out
Running a pump dry for even a short time may ruin gaskets & seals or the motor. Keeping the pool filled prevents this costly damage – your pump will last longer and run cooler when it’s always drawing in water, not air.
❌ 2. Poor Water Circulation, Filtration, & Sanitation
Improper Filtration: The pump & skimmer can only filter out contaminants (Dirt, algae, leaves, bugs, etc.) if the water level is correct. Too low, the pump will draw in air and can’t do its job, the filter gets less water to clean.
Improper circulation results in:
Uneven chemical distribution
Cloudy water
Algae growth
Maintaining the proper water level means cleaner, clearer water.
Water loss via leakage could result in the dilution of necessary chemicals, such as:
Cyanuric acid, leaving chlorine unprotected from the Sun’s UV rays
Calcium, resulting in corrosive water that will try to “eat” the calcium out of the pool structure and equipment
If you’re consistently losing water and refilling, you’re diluting and rebalancing chemicals more often, which is inefficient and costly. It’s better to keep the water in the pool to begin with, so your sanitizer and other chemical levels remain stable.
Pools with chronically low water levels are extremely susceptible to algae growth & black algae (technically not an algae, Black algae is a form of cyanobacteria that is resistant to chlorine, extremely difficult to kill once established in your pool, and can cause skin irritation and even hives in swimmers).
A pool that had chronically low water, resulting in zero filtration, circulation, & sanitation, and eventually developed a bad Black Algae infestation.
❌ 3. Equipment Strain
Heaters, salt cells, and automatic pool cleaners depend on consistent flow. For instance:
Pool Heaters require a certain flow rate – if the water is low and flow is reduced, the heater could overheat or shut off.
Suction & Pressure Side Pool Sweeps can malfunction if the pump isn’t drawing water due to a low water level.
Salt Cell Chlorine Generators require a constant flow of water to produce chlorine; without proper flow, your pool will not be properly sanitized.
By keeping the pool filled, you ensure all these components have the water they need, reducing wear and tear. In short, proper water level = happier pool = happier you.
❌ 4. Risk of Damage to the Pool Structure (in extreme cases)
If levels are extremely low or drop rapidly, liners can shrink, plaster can crack, and tile lines can separate.
This is rare unless water is significantly below normal, but still a risk.
The Bottom Line:
In summary, maintaining the proper water level safeguards your expensive pool equipment, keeps the water moving and filtered, and creates a more enjoyable swimming environment. It’s a simple habit that can save you from major headaches and expenses down the line.
How do I properly fill my pool?
“I’m going to throw the hose in my pool to fill while I run to the store.”
- Pool Owner Asking For Disaster
🚫STOP!🚫 Do not leave your pool unattended while filling with water. Here are some best practices for filling your pool with a garden hose or autofill:
Use a proper hose connection: Attach your garden hose to a convenient spigot (most pools have one nearby). It’s recommended (and often required by code) to have a hose bibb vacuum breaker on your spigot – this is a simple backflow prevention device. It stops pool water from siphoning back into your home’s drinking water if there’s a pressure drop. Make sure your hose connection is equipped with this for safety.
Never leave a filling pool unattended: This is crucial. Let’s say it again: “Never leave your pool unattended while it’s refilling.” Water can rise surprisingly fast, and an unattended hose can overflow your pool, wasting water and potentially flooding your yard or your neighbor’s property. Stay with the pool or set a timer on your phone to remind you to shut off the water. Many pool owners have learned the hard way that walking away “for a few minutes” can turn into an hour, and then the pool is overflowing. It’s simply not worth the risk – always keep an eye on the water level as you fill.
Monitor the water level as it fills: Know roughly how many inches you need to add and watch the pool markings (like the tile line or skimmer opening) to gauge progress. It can be helpful to mark the starting level and the desired level. Remember that an inch or two of water depth is hundreds of gallons, so even a high-flow hose will take some time to add an inch.
Avoid overfilling the pool: An overfilled pool can’t skim the surface properly (if water is above the top of the skimmer, debris won’t be pulled in). Most pools have an overflow or backwash line that will drain excess water, but consistently overfilling wastes water and could flood your yard. If you accidentally overfill a bit, you can usually correct it by running the pool pump to waste or backwashing the filter to lower the level. Just try to prevent it in the first place by watching the water level while filling.
Turn off the hose properly: When you reach the desired level, shut off the spigot. Coil up the hose and store it safely. Double-check that water is no longer flowing into the pool.
Be careful with autofill valves and floats: If your pool has an autofill and needs adjustment, then do so gently and per the manufacturer’s directions. Don’t force anything. If the autofill has a shutoff valve (it usually does), ensure it’s fully closed or open as intended – a half-closed valve could leak. After any adjustments, keep an eye on the next fill cycle to make sure it’s working correctly. Make sure the auto fill is free from debris and pests (frogs and other pests like to live in the auto fill area). Familiarize yourself with how to shut off the autofill water supply. If the valve ever malfunctions or leaks, you will need to turn the water supply off. The key is to notice unusual behavior like an autofill that is constantly running, or abnormally high water bills. Autofills can mask leaks. If you suspect an issue, turn off the autofill’s water supply and call a pool professional for an inspection.
Know how to shut off the water supply: Whether it’s your garden hose or an autofill line, know the location of the shutoff valve. In an emergency (like a hose popping out and spraying water everywhere, or an autofill stuck open), you’ll want to quickly stop the flow.
By adhering to these precautions, you can confidently top off your pool as needed while limiting any risk of property damage or equipment issues. Manual filling is straightforward – just treat it with the same attention you would when filling a bathtub (you wouldn’t leave that running unattended, either!). A little vigilance goes a long way in preventing accidents.
❗️DISCLAIMER❗️
This guide is provided for general informational purposes only and is not intended as professional engineering, plumbing, or construction advice. SWIMCLEAR POOLS LLC does not assume any responsibility or liability for any damages or loss resulting from the use of the information provided herein. Always consult with a licensed professional for specific issues related to your pool equipment, plumbing, electrical systems, or structural integrity. Any actions taken based on the content of this document are done so at your own risk. SWIMCLEAR POOLS LLC is not responsible for injuries, damages, or property loss resulting from misuse, neglect, or failure to follow safety guidelines.
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