Lawn Grass and Chlorinated Water
Date: Spring 2011
My home water shows the same chlorine level as my pool
water on the test kit. Will this harm my lawn or kill the grass seed and
prevents them from coming up?
The grass seed will still germinate and grow. The chlorine
dissipates. The problem of chlorinated water sometimes affecting the
appearance and health of the grass could be a concern mainly for areas
continuously exposed to chlorine such as around pools. The following
should be helpful:
Anthony R. Brach, PhD
Missouri Botanical Garden c/o Harvard University Herbaria
One or the other of your test kit is giving an error. You would find
drinking water having the level of chlorine found in a swimming pool very
nasty to drink. So your test kit must be giving a false high reading. That
is not unusual for colorimetric swimming pool test kits. Watering your
lawn/garden is not advisable generally. The pH may be wrong. Have your
drinking water and pool water tested by a professional. Something isn't
I notice you are from FL. You get a lot of sunlight. This can cause large
errors in the chlorine test.
Chlorinated water should not do your lawn any harm, but I am concerned
that the level in your tap water is the same as the pool.
Both tap water and pool water are chlorinated to kill bacteria and
other micro-organisms, and to reduce body wastes in the pool.
Chlorine will effectively deal with dead skin cells etc, and urine
that somehow manages to find its way into most swimming pools
(although NO-ONE seems to ever know how!!) Since the body waste issue
does not apply to tap water, there should be no need for the same
level of chlorination.
What kind of test kit did you use?
If it is designed to test tap water, you may have reached a maximum
level with the tap water, and then exceeded that level (but with no
further test change) with the pool water.
If you have used a pool test kit, then there are a few possibilities -
Your kit is old and the chemicals are stale. - your pool is badly
under-chlorinated. - Your tap water is severely over-chlorinated.
Without knowing the results of your tests it is impossible to know.
Lab Technician Barkly College - Secondary
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Update: June 2012