Water and pain killers

Two nights ago I took two acetaminaphen pm tablets at night, and awoke feeling less pain. It was easier to get going in the morning than it had been. Was it the pain killers or was it the water I've been gulping? Throughout the day I drank more water and did not take any arthritis pain killers. Last night I went to bed without the pms and this morning awoke again with less pain. It's not a scientific study but I think the water is working.