Flushing a Shower After Vacation to Limit Bacteria: EPA and DC Health Steps

As an Amazon Associate we earn from qualifying purchases.

This post covers flushing shower after vacation to prevent bacteria, using two sources. Flushing a shower after vacation is one of the clearest home steps in the sources. The EPA says that “Flushing the water in your home after periods of disuse (for example, while you are away or during remodeling) will remove stagnant water.” The DC Health handout says to “Run/flush all faucets and showerheads for at least 2 minutes, if they have been out of use for more than a week.” Those two lines are the core of this post. The sources do not say the flush removes every bacterium, and this post does not claim that it does.

Quick answer

Flush the shower and other outlets after a trip. The EPA lists being away as a reason to flush.
The DC Health handout uses a more than one week rule and says to run faucets and showerheads for at least 2 minutes.
The EPA describes the water being flushed as standing water that has been in the pipes and outlets, and it says to let the water run for approximately two minutes.
Limit splashing and spray during the flush, and step out of the spray area, according to the EPA.

Why a closed-up shower gets a flush

The EPA explains the problem in plain terms. Stagnant water “can lead to changes in water temperatures, lower levels of disinfectants and other conditions that provide opportunities for Legionella to grow.” When a house is closed up, the water in the pipes and at the shower sits still. Its temperature drifts toward the room temperature, and the disinfectant in it can fade. Those are the conditions the sources connect to growth.

The EPA also lists other sources of stagnant water. It names piping with low or no flow, capped pipes, and unused faucets such as a guest bathroom tap. A shower that has not been used during a trip fits that description, and so does a shower in a room that is rarely used at home.

Step 1: Check the shower and the nearby outlets

Before you flush, look at the shower head and the hose for buildup. The EPA says that “If you notice mineral build-up or slimy film on water fixtures, consider cleaning them more often.” If you see either, clean the head first, following the manufacturer’s method. The sources do not say to flush a dirty head without cleaning it, and they do not describe a flush as a cleaning step.

Plan the order of the outlets. The EPA says that if you are flushing a whole house, start with the tap nearest to where water enters the home and move outward from there. It also says cold water should be flushed before hot water.

Step 2: Run the water

The EPA says to “Open taps and let the water run for approximately two minutes to remove water that has been standing in the pipes and/or water outlets.” The DC Health handout says to run or flush all faucets and showerheads for at least 2 minutes if they have been out of use for more than a week. For the shower, that means turning on the cold and then the hot water at the head for the time the sources give.

The EPA says to “Run the cold water for two minutes.” It then says to “Run the hot water until it reaches its maximum temperature”. Those are the EPA’s words for the hot side. Running hot water to its maximum is a scald concern, so keep the spray direction away from you, and let the water reach temperature while you stay out of the spray.

The EPA has a second instruction for outlets that are used rarely. For those, it says to consider “running them on a weekly basis to flush them out.” A trip is a good time to start that habit at home.

Step 3: Reduce spray during the flush

The EPA says that during flushing, take care to minimize splashing and spray. It advises turning on an exhaust fan or opening a window, and stepping away from the area to avoid breathing in spray or small droplets that may contain bacteria. The DC handout does not describe a flush-specific spray step, so the EPA’s guidance is the one to follow here. The sources do not say how far to stand from the shower or how long to wait after the flush, so use common sense and keep out of the mist.

Step 4: Check the water heater and the temperature

The EPA says Legionella grows best between 80 and 120 degrees Fahrenheit. It says that keeping water in indoor plumbing above 124 degrees or below 80 degrees can help control the bacteria. The DC handout says to set water heaters to a minimum of 120 degrees and to consider 130 to 140 degrees. If you raised the heater setting before a trip, check that the setting is still what you want when you return.

Hot water at the faucet or shower “may present a scalding risk at temperatures above 117⁰F”, according to the EPA. Keep that in mind when you flush the hot side. Thermostatic mixing valves, placed close to the outlets, can manage scald risk, and the EPA says to follow the manufacturer’s instructions or use a professional for installation.

Cold water first, then hot

The EPA gives a specific order. “Cold water should be flushed before hot water.” It also says that when flushing the whole house, you start with the tap nearest to where water enters the home. For a shower, that means the shower is one outlet in a sequence, not a standalone step. The sources do not say how long a whole-house flush should last, only that each outlet should be run as described.

Long absences and reopening

The EPA’s section on buildings that reopen after low use says standing or stagnant water in premise plumbing “can lead to a change in water temperatures as well as lower levels of disinfectant residual.” Premise plumbing is the EPA’s term for the piping from the water meter to the tap. If you come back after a long absence, the same reasoning applies at home: the water in the pipes may have changed.

The EPA lists more causes of stagnant water than a trip. It says the other factors “include piping that is subject to low or no flow, or decreased water use such as capped pipes or unused faucets (e.g., in a guest bathroom).” A shower in a rarely used guest bathroom is a clear example, and it can be flushed with the same steps as a shower that sat idle during a trip.

For readers who also compare shower heads for flow and pressure, see our high pressure and water-saving shower head guide and the water-efficient hand-held shower head roundup. Those comparisons do not cover Legionella, and neither do the sources in this post.

Mistakes to avoid

Flushing for a few seconds and calling it done. The sources give a time, about two minutes, and the DC handout gives a minimum of 2 minutes.
Running hot water without thinking about scald risk. The EPA warns about temperatures above 117 degrees Fahrenheit.
Standing in the spray. The EPA asks you to step away from the area.
Assuming a flush replaces cleaning. The EPA treats cleaning of visible buildup as a separate step.

Frequently asked questions

Do I need to flush the shower after every trip?

The EPA lists being away as an example of disuse that calls for flushing. The DC handout ties the step to outlets out of use for more than a week. A trip that is longer than a week falls under both rules.

What about a short weekend away?

The DC handout’s threshold is more than a week. The EPA does not give a number for shorter periods, so the sources do not settle a weekend trip. Running the water briefly before the first shower is a reasonable habit, but the sources do not set a time for it.

Should I flush the water heater too?

The EPA says manufacturers may recommend flushing a water heater, and it names once a year, before moving in, after plumbing work, and when the water is discolored as examples. Follow the heater manual.

Is a flush enough to remove Legionella?

The sources do not say so. They describe flushing as a way to remove stagnant water and reduce growth conditions.

How we chose these sources

We used the EPA page “Legionella in the Indoor Environment” as the federal source on stagnant water and flushing. We used the DC Health handout “Preventing Legionellosis at Home” (2025) as a local government handout that sets a time rule. The CDC prevention page returned a 404 error and the CDC site returned 403 errors to our fetch tool, so no CDC text is quoted. Search results from county and state handouts were not used as sources.

What we could not verify

How much bacteria a flush removes from a shower. The sources do not measure it.
A flush time for a shower head that has been closed for a short period, such as a weekend.
Whether a flush is enough for a shower with a dirty head. The sources ask for cleaning as a separate step.
The CDC’s own flushing steps. The CDC pages were not available to us.

Sources

US EPA, “Legionella in the Indoor Environment”, https://www.epa.gov/node/271246 (opened 2026-10-29). Saved text: research/sources-20261029/B4/flushing-shower-after-vacation-to-prevent-bacteria–epa-indoor-environment.txt
DC Health, “Preventing Legionellosis at Home” (2025), https://dchealth.dc.gov/sites/default/files/dc/sites/doh/Preventing%20Legionellosis%20at%20Home_2025.pdf (opened 2026-10-29). Saved text: research/sources-20261029/B4/flushing-shower-after-vacation-to-prevent-bacteria–dc-health-home-handout.txt