Good idea (trying it by hand to see if that takes care of it). This
just started happening around the same time I adjusted the float to
stop the tank from continually overfilling. I have adjusted the float
and water supply several times, it lessens the hammer but I still get
some. Why would it be the toilet only (ie, none of the sinks,
sprinkler system, or washing machine do this)? If worst comes to
worst, what is the cost for a water hammer arrestor?