Environmental Public Health Division
Swimming Pools
HCPHES conducts inspections at public and
semi-public pools in Harris County for compliance with state
rules and regulations. This office inspects the following:
- Commercial Pools
- Home Owner
Association Pools
- Apartment Pools
- Hotel/Motel Pools
- Health Clubs
- Public / Private
Schools
- Townhomes/Condo
Pools
Frequently Asked Questions
Can a pool be green in the winter time
when there is no one swimming in the pool?
All public and semi-public pools must maintain water clarity all
year.
Do I have to get a permit to operate a
swimming pool in unincorporated Harris County?
At this time a permit is not required to operate a swimming pool
in unincorporated Harris County.
What do I do if there is a fecal
accident in the pool?
Guidelines from Center for Disease Control is listed as
follows. Link
to the CDC
- These recommendations are for responding to
fecal accidents in chlorinated recreational water venues.
- Improper handling of chlorine-based
disinfectants could cause injury. Follow proper occupational
safety and health requirements when following these
recommendations.
Important
Background Info
WHAT ARE
RECREATIONAL WATER ILLNESSES (RWIs)?
What is the first thing
that pops into your head when you think about water safety?
Drowning? Slipping? Lightning? All good answers, and all are
very important. But, did you know that germs can contaminate
swimming water? These germs cause RWIs that have made many
people sick.
RWIs are caused by
waterborne germs such as “Crypto” (KRIP-toe), short for
Cryptosporidium, Giardia (gee-ARE-dee-uh), E.
coli O157:H7, and Shigella (Shi-GEL-uh).
HOW ARE RWIs
SPREAD?
RWIs are spread by
accidentally swallowing pool water that has been contaminated
with germs that cause diarrhea. How? If someone has diarrhea,
that person can easily contaminate the pool. Think about it.
Pool water is shared by every swimmer and is not sterile.
The good news is that
germs causing RWIs are killed by chlorine. However, chlorine
doesn’t work right away. It takes time to kill germs and some
germs like Crypto can live in pools for days. Even the best
maintained pools can spread illness.
SHOULD ALL FECAL
ACCIDENTS BE TREATED THE SAME?
No.
A diarrheal fecal accident
is a higher risk event than a formed stool accident. With most
diarrheal illnesses, the number of infectious germs found in
each bowel movement decreases as the diarrhea stops and the
person’s bowel movements return to normal. Therefore, a formed
stool is probably less of a risk than a diarrheal accident that
you may not see.
A formed stool may contain
no germs, a few, or many that can cause illness. You won’t know.
The germs that may be present are less likely to be released
into the pool because they are mostly contained within the
stool. However, formed stool also protects germs inside from
being exposed to the chlorine in the pool so prompt removal is
necessary.
Germ Inactivation
Time for Chlorinated Water*
|
Germ |
Time |
|
E.
coli
O157:H7
Bacterium |
Less than 1 minute |
|
Hepatitis A
Virus |
about 16 minutes |
|
Giardia
Parasite |
about 45 minutes |
|
Cryptosporidium
Parasite |
about 9600 minutes (6.7 days) |
|
*
1ppm (1mg/L) chlorine at pH 7.5 and 77°F (25°C) |
SHOULD YOU TREAT A
FORMED FECAL ACCIDENT AS IF IT CONTAINS CRYPTO?
No. In 1999, pool staff
volunteers from across the country collected almost 300 samples
from fecal accidents that occurred at waterparks and pools. CDC
then tested them for Crypto and Giardia. None of the
sampled fecal accidents tested positive for Crypto but
Giardia was found in 4.4% of the samples collected. These
results suggest that formed fecal accidents pose only a very
small Crypto threat, but should be treated as a risk for
spreading other germs (such as Giardia). Remember a
diarrheal fecal accident is considered to be a higher risk event
than a formed stool fecal accident.
What do I do about
formed stool in the pool?
Formed stools can act as a
container for germs. If the fecal matter is solid, removing the
feces from the pool without breaking it apart will decrease the
likelihood of pool contamination. In addition, RWIs are more
likely to be spread when someone who is ill with diarrhea has a
fecal accident in the pool.
-
Direct everyone to leave the pool. If you
have multiple pools that use the same filter—all pools will
have to be shut down. Do not allow anyone to enter the
contaminated pool(s) until all decontamination procedures
are completed.
-
Remove as much of the fecal material as
possible using a net or scoop and dispose of it in a
sanitary manner. Clean and disinfect the net or scoop (e.g.,
after cleaning, leave the net or scoop immersed in the pool
during disinfection). VACUUMING STOOL FROM THE POOL IS NOT
RECOMMENDED.
-
Raise the chlorine to 2 ppm (if less than 2
ppm), and ensure the pH is between 7.2 - 7.5. This chlorine
concentration was selected to keep the pool closure time to
approximately 30 minutes. Other concentrations or closure
times can be used as long as the CT inactivation value (Footnote
1)is kept constant.
-
Maintain the chlorine concentration at 2.0
ppm, pH 7.2 - 7.5, for at least 25 minutes before reopening
the pool. State or local regulators may require higher
chlorine levels in the presence of chlorine stabilizers such
as chlorinated isocyanurates. Ensure that the filtration
system is operating while the pool reaches and maintains the
proper free available chlorine concentration during the
disinfection process.
-
Establish a fecal accident log. Document each
fecal accident by recording date and time of the event, note
whether formed stool or diarrhea, and note the chlorine
levels at the time or observation of the event. Before
reopening the pool, record the pH, the procedures followed
in response to the fecal accident (including the process
used to increase chlorine levels if necessary), and the
contact time.
What do I do about
diarrhea in the pool?
Those who swim when ill
with diarrhea place other swimmers at a significant risk for
getting sick. Diarrheal accidents are much more likely than
formed stool to contain germs. Therefore, it is important that
all pool managers stress to patrons that swimming when ill with
diarrhea is an unhealthy pool behavior.
-
Direct everyone to leave the pool. If you
have multiple pools that use the same filter—all pools will
have to be shut down. Do not allow anyone to enter the
contaminated pool(s) until all decontamination procedures
are completed.
-
Remove as much of the fecal material as
possible using a net or scoop and dispose of it in a
sanitary manner. Clean and disinfect the net or scoop (e.g.,
after cleaning, leave the net or scoop immersed in the pool
during disinfection). VACUUMING STOOL FROM THE POOL IS NOT
RECOMMENDED.
-
Raise the free available chlorine
concentration to 20 ppm (mg/L) and maintain the pH between 7.2 and 7.5. This
chlorine and pH level should be sufficient to inactivate
Cryptosporidium and should be maintained for at least 8
hours, equivalent to a CT inactivation value of 9600.
(Footnote 2)
-
Ensure that the filtration system is
operating while the pool reaches and maintains the proper
chlorine level during disinfection. If necessary, consult an
aquatics professional to determine and identify the
feasibility, practical methods, and safety considerations
before attempting the hyperchlorination of any pool.
-
Backwash the filter thoroughly after reaching
the CT value. Be sure the effluent is discharged directly to
waste and in accordance with state or local regulations. Do
not return the backwash through the filter. Where
appropriate, replace the filter media.
-
Swimmers may be allowed back into the pool
after the required CT value has been achieved and the
chlorine level has been returned to the normal operating
range allowed by the state or local regulatory authority.
-
Establish a fecal accident log. Document each
fecal accident by recording date and time of the event, note
whether formed stool or diarrhea, and note the chlorine
levels at the time or observation of the event. Before
reopening the pool, record the pH, the procedures followed
in response to the fecal accident (including the process
used to increase chlorine levels if necessary), and the
contact time.
Footnote 1: CT refers to
concentration (C) of free available chlorine in ppm multiplied
by time (T) in minutes. If pool operators want to use a
different chlorine concentration or inactivation time, they need
to ensure that CT values always remain the same (See Figure 1
for examples).
Footnote 2: Many
conventional test kits cannot measure free available chlorine
levels this high. Use chlorine test strips that can measure free
available chlorine in a range that includes 20 ppm (such as
those used in the food industry) or make dilutions for use in a
standard DPD test kit using chlorine-free water.
For more information about
the CDC Fecal Accident Recommendations, please go to
http://www.cdc.gov/healthyswimming/fecal_response.htm
Pool Disinfection
time
How long does it take to
disinfect the pool after a fecal accident? This depends on what
type of fecal accident has occurred and at which chlorine levels
you choose to disinfect the pool. If the fecal accident is
formed stool, follow Figure 1, which displays the specific time
and chlorine level needed to inactivate Giardia. If the
fecal accident is diarrhea, follow Figure 2, which displays the
specific time and chlorine levels needed to inactivate Crypto.
Figure 1-Giardia
Inactivation for Formed Fecal Accident
|
Chlorine Levels (ppm) |
Disinfection Time* |
|
1.0 |
45
minutes |
|
2.0 |
25
minutes |
|
3.0 |
19
minutes |
|
*
These closure times are based on a 99.9% inactivation of
Giardia
cysts by chlorine, pH 7.5, 77° F (25° C). The closure
times were derived from the Environmental Protection
Agency (EPA) Disinfection Profiling and Benchmarking
Guidance Manual. These closure times do not take into
account “dead spots” and other areas of poor pool water
mixing. |
Figure
2-Crypto Inactivation Time for Diarrheal Accident
|
Chlorine Levels (ppm) |
Disinfection Time |
|
1.0 |
6.7 days |
|
10 |
16
hours |
|
20 |
8
hours |
CT value
is the concentration (C) of free available chlorine in ppm
multiplied by time (T) in minutes (CT value = C x T ). The CT
value for Giardia is 45 and the value for Crypto is
9600. If you choose to use a different chlorine concentration or
inactivation time, you must ensure that the CT values remain the
same. For example, to determine the length of time needed to
disinfect a pool at 15 ppm after a diarrheal accident use the
following formula: C x T = 9600. Solve for time: T= 9,600 ÷ 15
ppm = 10.7 hours. It would take 10.7 hours to inactivate Crypto
at 15 ppm. You can do the same for Giardia by using the
CT of 45.
|
Pool Closures
Fecal accidents are a concern and an
inconvenience to both pool operators and patrons. Pool
operators should carefully explain to swimmers the need
to close the pool in response to a fecal accident for
their own health and safety. Understanding that pool
closure is necessary for proper disinfection and
protection of the health of swimmers is likely to
promote support rather than frustration. Pool closures
allow chlorine to do its job and protect your swimmers
from RWIs |
Links
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