Long term effects of water chlorination are very much debatable.
There are long term side effects of chlorine consumption but it is generally being regarded as relatively low risk and certainly the benefits outweigh the risks of drinking untreated, suspect water.
If used appropriately, left to stand for enough time I doubt there is much danger to health in using the tablets for that time.
Possibly get a physical filtration device if you are concerned?
When I talk of long term side effects there are some studies that suggest lifetime chlorinated water consumption (i.e tap water) may lead to increased bladder cancer, thyroid hormone disruption (as iodine and chlorine are both halogens) but if you look into it is no massive effect and obviously it makes sense for tap water to be chlorinated as opposed to everyone ending up with nasty waterborne illnesses all the time.
Tablet treated water will be higher in chlorine than water at the tap, but if it's for a 6 month period I can't imagine too much harm.
From what I remember it isn't chlorine itself that has negative effects, Instead it is compounds formed within the water, trihalomethanes IIRC.
I don't have any qualms about drinking tap water, or using purification tablets if I needed to.