4 Common Reasons for a High Water Bill – Steps on How to Find

Did you just receive a high water bill? Do you want to figure out where the leak is today? Continue reading for instructions on isolating your mysterious leak!


Getting an expensive water bill can be very frustrating, especially when you had no idea that you had a water leak in your home. The most common causes for a high water bill are running toilets, leaking main water services, irrigation and swimming pool leaks, and slab leaks. Today, we are going to share with you the first steps that we take to narrow down where mysterious leaks are coming from.


Step 1: Confirming that a leak is currently present


Figure 1 – Water Meter Box

Go out to the sidewalk in front of your home and locate your water meter box. It should look similar to the water meter box pictured in (Figure 1).







Figure 2 – Water Meter

Next, remove the lid to the box to uncover the water meter, as shown in (Figure 2).







Most homes in Maricopa have a digital water meter, which is great for figuring out exactly how bad a leak is in real time! These water meters automatically cycle through several different readings, including one that provides the current gallons per minute of water passing through the water meter. If you have an analog water meter, then you should look for a small, blue triangle or a small, red gear (your analog water meter should have one or the other). This small component will rotate when water is passing through the water meter. Make sure no one in your home is running any water. Make sure your dishwasher and washing machine are both not running. If no water is currently being consumed, then your water meter should read “0.00 GPM” (0.00 gallons per minute). If any value other than 0.00 is displayed, then water is passing through your water meter. If a reading of “0.00 GPM” is observed, then you may still have a leak, but one is certainly not present in your underground domestic water lines, as these are always pressurized, and are therefore not susceptible to intermittent leaks. If you are so lucky as to have a reading of “0.00 GPM,” then call a professional to diagnose further. You may have a toilet that periodically runs. You should listen to these closely for sounds of water running. Certain irrigation issues and swimming pool leaks can also waste water on a non-constant basis. If your water meter displays anything other than “0.00 GPM” on the gallons per minute reading, then proceed to step 2 below.


Step 2: Checking your main water service for a leak

Your main water service is the water line that runs from the water meter, up to your house. Obviously, this water line is underground, so you may be wondering how a homeowner can check it for leaks without any fancy equipment. Well, leak detection equipment is used to pinpoint underground leaks, but you can determine whether or not a leak is present in this water line very easily without any tools at all!

Figure 3 – Main Water Shut-Off Valve

Locate your main water shut-off valve, as seen in (Figure 3). Turn the shut-off valve 90 degrees clockwise, so that the handle is perpendicular to the pipe. Note: If your looks like a wagon wheel, then your home has an old style gate valve, and not a modern ball valve, as shown in this article. Attempting to close a gate valve may result in the valve leaking, so we highly recommend calling a professional to replace it with a ball valve before continuing.



Open the hose bibb located near your main water shut-off valve to confirm that the valve is working. After several seconds, water should stop running out of the hose bibb. If it does not, then you need your main water shut-off valve replaced before continuing. If your main water shut-off valve is working, then return to your water meter and wait for the gallons per minute reading to appear. If a positive reading is still observed, then you have determined that your main water service is leaking. If your water meter now displays “0.00 GPM,” then you have ruled out your main water service is the source of your leak, and you may turn your main water shut-off valve back on and continue to step 3 below.


Step 3: Checking your irrigation and swimming pool plumbing for leaks

If you do not have irrigation or a swimming pool, then you may skip this step. Just like the logic followed in step 2, we are now going to isolate these plumbing lines from the rest of the system. Look for what is called a pressure vacuum breaker, as shown in (Figure 4).

Figure 4 – Pressure Vacuum Breaker

The purpose of this device is to prevent contaminated irrigation or swimming pool water from back-flowing into your home’s domestic water supply. Shut it off while you check your water meter once again for the real-time gallons per minute reading, as done is step 2 (confirming that it is shutting off effectively is, unfortunately, not as straight forward as with the main water shut-off valve). If water consumption is no longer taking place, then you have isolated the leak. If water consumption is still taking place, then proceed to step 4, but do not forget to turn these water valves back on after this entire process.


Step 4: Checking for a hot water “slab leak”

Most homes in Maricopa have water lines that run under their slab all throughout the dwelling. When one of these water lines leak, we call the leak a “slab leak” in the plumbing trade. A hot water slab leak can be ruled out by shutting the water off at the inlet to the hot water heater, as shown in (Figure 5).

Figure 5 – Water Heater Shut-Off Valve

Again, the valve should turn 90 degree clockwise, so that the handle is perpendicular to the water pipe. After turning the hot water heater shut-off valve off, turn on the hot water at a faucet in either a bathroom or your kitchen to confirm that, after several seconds, hot water flow discontinues, and then reassess your water meter. If the water meter no longer registers water flow, then you have a hot water slab leak. If, however, water flow is still registering, then you likely have a leaking cold water line under the dwelling of your home.




Figure 6 – Toilet Shut-Off Valve

It is, however, possible that if your rate of water loss is very small, that a toilet is simply running. Even though these were considered in Step 1, very minor water use by a toilet can be rather difficult to detect. The shut-off valves beside each toilet, as shown in (Figure 6), can be shut-off, but this is not recommended, especially if they are original to your home. Hard water minerals can, like older style gate valves, cause these valves to leak upon operating them. A dye test can be performed, but it is more practical at this point call a professional to replace your toilet shut-off valves in order to rule out a running toilet.



Most homes in Maricopa were built with PVC main water lines. PVC becomes brittle due to the chlorine in our water over time. A repair can certainly be made, but if you plan to keep your home long-term, then a replacement of your main water line may be worth considering, especially if it has leaked multiple times over the years. Most homes in Maricopa have fairly short main water lines, so a replacement can be surprisingly inexpensive. Even if the main water line runs under your home’s driveway, it can usually be replaced without demolition of any portions of the driveway. The modern piping used, called PEX, is manufactured to outlive all of us!

As for slab leaks, it is usually more cost effective to replace these water lines with PEX. This process involves abandoning the existing, underground, leaking water line, and rerouting it overhead. Doing this avoids invasive excavation through your home’s concrete slab, saving you potentially costly flooring reconstruction. Very modern homes are actually being built with overhead PEX water lines! Although patching a leaking underground water line (called a “spot repair” in the plumbing trade) leaves in operation the remaining portions of a water line that has displayed unreliability, it is occasionally necessary to do this, which can be very costly with a post-tension slab, which most homes in Maricopa have been built with. The most common scenario in which a spot repair is unavoidable is when the leaking water line feeds a kitchen island sink. Feeding such a fixture overhead would require installing a beam that runs from the ceiling down to the kitchen island.

In some cases, unnoticed leaks cause water damage in a home. If not caught early, this surfaced moisture can increase to a flood. If you have a slab leak, a plumbing professional should check for unnoticed water damage, so that any water damage that may be present can be remediated before mold growth occurs. When water damage does occur, most homeowners insurance policies will also at least partially cover plumbing repairs.

At Plumbers of Maricopa, we are experts at detecting and repairing wwater leaks of all types, and we are accustomed to facilitating insurance claims on behalf of our customers, so call us at 520-600-5700 today!