Why Is My Water Bill So High? 7 Common Causes in Garland, TX Homes

A sudden jump in your water bill is one of the most common reasons Garland homeowners call us. While a slab leak is often the first thing people suspect, there are actually several possible causes, and identifying the right one saves time and money.

Before diving into the seven causes, it helps to reframe how you read your bill. The dollar amount can rise for reasons that have nothing to do with a leak — seasonal rate tiers, sewer charges tied to winter averages, or a rate increase from the utility. The number that actually tells you something is your metered usage, typically shown in gallons or in units of 100 cubic feet, where one unit equals about 748 gallons. If your usage has climbed while your household routine has not, that gap is real water going somewhere, and one of the causes below is responsible. Keep a few past bills handy so you can compare usage month over month and year over year, since a leak often shows up as a usage figure far above the same month last year.

1. A Slab Leak

Water escaping from a supply line beneath your foundation is one of the most common and most costly causes of a high water bill in older Garland neighborhoods with original copper plumbing.

A slab leak is often the largest single driver of a sudden bill spike because it runs continuously, day and night, under pressure. A moderate slab leak can waste 100 or more gallons a day, which is roughly 3,000 gallons a month, and a larger supply-line failure can lose far more. Because the water disappears into the soil under your home rather than surfacing where you can see it, a slab leak can run for months before anything visible appears. The telltale signs are a warm spot on the floor from a leaking hot-water line, the faint sound of running water with everything off, a musty smell, or new cracks in flooring. Detection tip: run the meter test described later — if the meter moves with the house shut off and there are no visible leaks anywhere, a slab leak is a leading suspect and calls for professional slab leak detection.

2. A Running Toilet

A worn flapper valve can silently waste hundreds of gallons a day. Add a few drops of food coloring to the tank; if color appears in the bowl without flushing, the flapper is leaking.

A running or silently leaking toilet is one of the most underestimated causes of a high bill because it wastes water quietly and constantly. A flapper that no longer seals lets water trickle from the tank into the bowl around the clock, and depending on how bad the seal is, a single toilet can waste anywhere from a modest trickle to several hundred gallons a day. Multiply that across a full billing cycle and a single bad flapper can account for thousands of gallons. Detection tip: the food-coloring test is the fastest check — put a few drops in the tank, wait 10 to 15 minutes without flushing, and look for color bleeding into the bowl. Also listen for a toilet that periodically refills on its own, which is the sound of the tank topping up water it has lost. A flapper is inexpensive and one of the easiest fixes on this list.

3. An Irrigation System Leak

Cracked risers or a damaged main irrigation line can waste significant water while appearing on the surface as normal lawn watering, especially common in newer Firewheel-area and East Garland subdivisions with in-ground sprinkler systems.

Irrigation leaks are sneaky because the system runs on a schedule, often before dawn, so you rarely watch it operate. A cracked riser, a broken sprinkler head, or a fracture in the buried main line can dump large volumes of water each cycle, and a leak on the pressurized supply side of the valves can run continuously between cycles. Because North Texas summers already push irrigation usage up, a leak here can hide inside what looks like normal seasonal watering. Detection tip: run each zone manually in daylight and watch for heads that spray unevenly, geysers, bubbling at the base of heads, or soggy areas that never dry out. If the meter keeps moving when the controller is off and the house is shut off, suspect a leak on the irrigation supply line before the valves. Repairing irrigation leaks promptly protects both your bill and your foundation, since oversaturated soil next to the slab contributes to movement.

4. A Leak in the Water Line Between the Meter and the House

This underground line is a common, often-overlooked leak point, particularly in older sections of Garland with aging service lines.

The service line that carries water from the meter at the curb to your home is buried in the yard, and when it develops a leak, the water often soaks quietly into the ground with little to show for it on the surface. Older service lines in established parts of Garland, Mesquite, and Richardson are common culprits as they age and the surrounding clay shifts. Because this line is pressurized and runs all the time, a leak here can waste a great deal of water continuously. Detection tip: this is where the two-part meter test earns its keep. If the meter moves with everything off but stops when you close the shutoff valve at the house, the leak is on the buried service line between the meter and the home, and it calls for water line repair rather than work under the slab. Watch also for a soggy or unusually green strip in the yard tracing the path from the meter toward the house.

5. A Dripping Fixture

A slow drip from a faucet or shower head adds up over a billing cycle. It's one of the easiest causes to check and the least expensive to fix.

It is easy to dismiss a dripping faucet as trivial, but drips are relentless. A faucet dripping about once per second can waste on the order of a few thousand gallons over a year, and a home with several dripping fixtures or a leaking showerhead can see that add up noticeably on the bill. Hot-water drips are doubly costly because you pay to heat the water you then lose. Detection tip: walk the house and check every faucet, showerhead, tub spout, and hose bib, including the outdoor spigots that are easy to forget. Look and listen for slow drips, and check under sinks for dampness at supply-line connections and P-traps. Most drips come down to a worn washer, cartridge, or O-ring and are inexpensive to repair, making this one of the highest-value places to start.

6. A Water Softener or Filtration System Malfunction

Systems that regenerate on a timer rather than based on actual use can cycle more often than necessary, using more water than expected.

Water treatment equipment is often overlooked because it lives in the garage or a utility closet and works automatically. A water softener flushes its resin bed during a regeneration cycle, and a unit stuck in a continuous regeneration loop, set to regenerate far too frequently, or suffering a failed valve can send a surprising amount of water straight down the drain without you ever noticing. Detection tip: check whether you hear the softener running water at odd hours or seemingly nonstop, and inspect the drain line for continuous flow when no regeneration should be happening. If the system uses a timer, consider whether it is set to regenerate more often than your household actually needs. A malfunctioning softener can quietly inflate a bill for months, so it is worth ruling out, particularly in homes that added treatment equipment to deal with hard North Texas water.

7. Seasonal Usage Changes

Increased outdoor watering during hot North Texas summers is a legitimate, non-leak explanation, though it's worth ruling out the other six causes first if the increase seems unusually high.

Sometimes the higher bill is simply the season doing its job. During the hot, dry North Texas summer, lawn and garden watering, filling a pool, more frequent showers, and guests can all push usage up legitimately. Utilities also often calculate sewer charges based on a home's average winter water use, so summer irrigation can raise the water portion of the bill without changing sewer charges, which sometimes surprises homeowners. Detection tip: compare this month's usage to the same month a year ago rather than to last month, since summer-to-summer is the fair comparison. If this summer looks like last summer, seasonal usage likely explains it. If it is dramatically higher than the same period in prior years, the season alone probably is not the answer and one of the first six causes deserves a closer look.

When a High Bill Actually Means a Slab Leak

Because a slab leak is the most expensive of these causes to ignore, it helps to know the specific pattern that separates it from the others. Not every high bill is a slab leak, but certain combinations of clues make one likely and warrant prompt professional attention.

• The meter moves with every fixture, appliance, and irrigation zone off, and it keeps moving even after you've checked toilets, faucets, and the softener.
• A warm or damp spot has appeared on the floor, most often on tile or hardwood, pointing to a leaking hot-water line under the slab.
• You hear the faint sound of running water through the floor or a wall when the house is silent.
• A musty smell, new flooring or drywall cracks, or reduced water pressure has shown up alongside the higher bill.
• Closing the main shutoff at the house stops the meter — indicating the loss is inside or under the home rather than out on the yard service line.

When those signs cluster together, a slab leak moves to the top of the list, and the right next step is professional detection rather than more guessing. Because a slab leak wastes water continuously and can begin to affect the soil supporting your foundation, it is the one cause on this list where waiting reliably makes things worse and more expensive.

How to Read Your Water Meter Step by Step

The meter test is the most powerful diagnostic tool available to a homeowner, and it separates a leak from a lifestyle change in under an hour. Here is how to run it properly.

1. Shut off every water-using fixture and appliance: faucets, showers, the dishwasher, washing machine, ice maker, and the irrigation controller.
2. Open the meter box near the curb and note the reading, watching the small leak or flow indicator for any motion.
3. Wait one to two hours without using water, then read the meter again — any change confirms water is being used somewhere with everything off.
4. To split indoor from outdoor, close the main shutoff valve at the house and repeat: if the meter now holds still, the leak is on the buried service line in the yard; if it keeps moving, the leak is inside or under the home.
5. Record what you find. These results tell a technician whether to focus on the yard service line, the irrigation system, or a slab leak, saving time on the visit.

Putting Numbers to the Waste

It is easier to take a high bill seriously when you can see how quickly small leaks accumulate into real gallons and real dollars. None of the figures below require special equipment to appreciate; they simply show why a problem that looks minor on any given day becomes expensive over a full billing cycle.

• A slab leak losing 100 gallons a day wastes about 3,000 gallons a month and roughly 36,500 gallons a year, all of it billed to you and none of it used.
• A silently running toilet with a bad flapper can waste anywhere from a few hundred to over a thousand gallons a day in a bad case, quietly rivaling a slab leak.
• A faucet dripping once per second adds up to several thousand gallons over a year, and a hot-water drip also wastes the energy used to heat it.
• A single broken sprinkler head or cracked riser can discharge many gallons per minute while a zone runs, so a leak that survives several cycles a week is a major contributor.
• A water softener stuck in a regeneration loop can send hundreds of gallons down the drain per day with no visible sign inside the house.

Stack two or three of these together and a bill that doubled suddenly makes sense. The encouraging news is that the cheapest fixes on this list often eliminate the largest surprises, which is why a methodical walk-through pays off before you assume the worst.

Why Garland and DFW Homes See These Problems

Several local conditions make the causes above more common here than they would be in other parts of the country, and understanding them helps you know where to look first. North Texas water is hard, carrying dissolved minerals that gradually build up in fixtures, water heaters, and valves; that scaling is why so many homes run softeners in the first place, and it is also why aerators clog and toilet parts wear out faster. The expansive Houston Black clay soil shifts with the seasons and stresses both the buried service line in your yard and the supply lines under your slab, making leaks in those hidden runs more likely as a home ages. And the long, hot summers drive irrigation usage sky-high from roughly May through September, which both raises legitimate usage and hides irrigation leaks inside a normal-looking seasonal bump.

The age of the housing stock matters too. Many homes across Garland, Mesquite, Richardson, and the older sections of surrounding suburbs were built decades ago with copper supply lines now nearing the end of their roughly 50-year service life, and with cast-iron or galvanized components that corrode from the inside out. As those materials age in our shifting clay, the odds of a slab leak or a service-line leak rise, which is exactly why a mysteriously high bill in an established North Texas neighborhood deserves a careful look rather than a shrug.

What It Costs to Wait

One theme runs through every cause on this list: the price of ignoring a high bill is almost always higher than the price of investigating it. Water is metered continuously, so a leak does not pause while you decide whether to act; it keeps running every hour of every day, and the gallons you saw on this month's bill are simply the first installment. A slab leak that wastes 3,000 gallons a month does not stay a billing nuisance for long, because the same water is also softening the soil that supports your foundation, and foundation movement is far more expensive to correct than a plumbing repair.

The same logic applies down the list. A running toilet or a stuck softener quietly bills you month after month until someone finally checks. An irrigation leak keeps saturating the ground next to your slab through every summer cycle. A service-line leak in the yard keeps washing out soil and inflating the bill until the line is repaired. None of these problems improve on their own, and every one of them is cheaper to fix early than to discover later as water damage, foundation stress, or a bill that has quietly doubled for half a year. That is why a methodical check the very month you notice a spike is one of the highest-return hours a homeowner can spend.

How to Narrow It Down

1. Compare metered usage across recent bills and against the same month last year to confirm the increase is real and not just a rate change
2. Check your water meter with all fixtures off to confirm active water flow
3. Test toilets for silent leaks using the food coloring method
4. Walk the home for dripping faucets and check the water softener for continuous or too-frequent regeneration
5. Run irrigation zones individually in daylight and check for pooling, geysers, or low pressure
6. If usage confirms a leak but the source isn't obvious, schedule professional leak detection

Working through these steps usually points to one clear culprit, and many of them — a flapper, a washer, a sprinkler head — you can address yourself. When the meter confirms a leak but the source stays hidden, or when the warning signs point under the slab, our team provides professional water leak detection, water line repair, and slab leak detection across Garland, Richardson, Plano, Rowlett, Mesquite, Wylie, Sachse, Murphy, and Rockwall. Finding the true cause early keeps a puzzling bill from turning into water damage, and gives you back both your water and your peace of mind.