Your water bill doubled overnight: the order to check things in

A water bill that suddenly jumps is alarming, partly because water is not cheap here and partly because it usually means water is going somewhere it should not. The good news is that the causes fall into a short list, and they have a natural order to check them in, from the cheapest and most common to the rarest and most expensive. Working that order yourself, before you call a plumber, will often either solve the problem or tell you exactly what to hand off. This is that order, tuned for a San Tan Valley home on EPCOR or Arizona Water Company service.

Start by confirming it is a leak, not a reading

Before hunting for a leak, rule out the boring explanations, because they are common. A bill can spike from a meter estimate followed by a correction, a rate change, a season of heavier irrigation, house guests, or a new appliance. Check whether your usage actually rose or just your charge, and whether the reading was estimated. If the usage genuinely climbed and nothing in your habits explains it, then you are looking for a leak, and the meter test tells you for sure: shut off all water, read the meter, wait an hour without using any, and read again. Movement means water is escaping somewhere.

Suspect number one: the toilet

If the meter confirmed a leak, start with toilets, because a running or silently leaking toilet is the most common cause of a spike and the easiest to miss. A toilet can leak from the tank into the bowl continuously without a sound, wasting a startling amount of water day and night. The test is simple: put a few drops of food coloring in the tank, wait fifteen minutes without flushing, and check the bowl. If color appears in the bowl, the flapper is leaking and the toilet is your culprit. That is usually a cheap part, and it is covered in more depth on the toilet repair page. On this water, scale on the flapper is the usual reason it stops sealing.

Suspect number two: irrigation and the desert-landscaping leak

If the toilets are clean, look outside, because in San Tan Valley a huge share of hidden water loss never happens in the house at all. Drip systems and buried irrigation lateral lines run through decomposed granite, and when one cracks it leaks straight into dry soil with no puddle to give it away. The water simply vanishes underground, and the only evidence is the bill. This is why a bill can climb through spring and summer with nothing visibly wrong indoors.

To check, isolate the irrigation from the house. If your system has its own shutoff, turn the irrigation off and repeat the meter test on the house alone. If the house holds steady but the meter moved with irrigation on, the leak is in the yard. Walking the drip lines for an unexpectedly green or soft patch can sometimes spot it, but buried lateral breaks often hide, which is where professional leak detection that isolates zones earns its keep.

The quick indoor sweep, while you are at it

Before moving to the expensive suspects, walk the house once and check these.

• Under every sink, for damp cabinet floors or a weeping supply stop
• Around the water heater base, for pooling that signals a failing tank
• Behind the washing machine, for a leaking hose or connection
• Every faucet, for a drip, and every aerator, for a leak at the base
• Any exterior hose bib, for a valve that no longer shuts fully

A weeping supply stop or a dripping faucet is a small faucet repair, not a mystery, and catching it here saves a service call for something you can point to.

Suspect number three: the slab

If the toilets are sealed, the irrigation is isolated and clean, and the indoor sweep found nothing, but the meter still moves with the whole house shut down, the leak has moved into the more serious territory of a line under the slab. The tells are a warm spot on the floor for a hot-side leak, the sound of running water with everything off, and damp flooring. This is the point to stop testing and call, because a slab leak is located with acoustic and thermal equipment rather than by guesswork, and every day it runs is water you are paying for and fill being undermined under your slab.

The order at a glance

Cheapest and most common at the top. Work down until the meter goes still.

The bottom line

A doubled bill almost always has a findable cause, and the order is what saves you money: rule out the reading, dye-test the toilets, isolate the irrigation, sweep the fixtures, and only then suspect the slab. Most spikes are solved in the first two steps for the price of a flapper. When the trail leads under the concrete, that is the one to hand off, because locating it precisely is what keeps the repair small and the floor intact.

Common questions