Sokitume. In Australia Rheem always state that a HT55 valve should drip at least 1 litre per day, A HT55 valve is a high temp & over press relief valve, When water is heated, it expands – & therefore the valve releases the additional pressure. Any Relief valve is a safety valve & should never!! ever!! be blocked or capped.
You could check your incoming pressure & possibly install a Press limit valve & also a cold water pressure relief valve, but call a Licensed Rheem plumber to be sure.