Outer Limits 4x4 Board

i got a stainless steel fuel tank in the back yard (petrol) and was curious if i could turn it into a water tank safely? just worried bout the water getting contaminated thats all? could you clean it out with something so there wouldnt be a health risk?

it would take a steamer pipe down into and a lot of detergent,followed by bicarb and lemon juice(mixed together ).