What could be the reasons to get low bp often, to someone who takes food and drinks water properly. ?

Salt? Weight?: Low BP could be from very low weight (underweight), or inadequate intake of salt. Many people overdo it on avoiding salt, but you need salt, especially in hot weather, to keep BP normal. An active elderly friend had this problem last summer with dizziness. Very costly hospital workup elsewhere was negative. I told him to start using salt and push fluids: cured in 24hrs! see md if it persists.