How long does hydrochlorothiazide stay in your system?

It takes approximately 3.5 days for hydrochlorothiazide  to be removed from the body.

Hydrochlorothiazide has an elimination half-life of 6 to 15 hours. The half life is used to estimate how long it takes for a drug to be eliminated from the body. Generally it takes 5.5 half-lives for a drug to be removed from the body, when it is deemed to no longer have an effect. Therefore for Hydrochlorothiazide, if we use the longest half-life, it would take approximately 82.5 hours (5.5 x 15 hours) which is approximately 3.5 days to be removed from your system.

Elimination of a drug varies from person to person due to factors like age, weight, other medications taken, or other medical conditions present, also kidney function, liver function etc. Therefore half life is used as a guide or an estimate of how long it may take for the drug elimination.