I have a stall shower that I haven't used for years because a prior owner ruined it by bad caulk job and resulted in mildew and backing board saturation. I had to remove some tiles near to the floor and spray with bleach solution. So it has been dormant ever since. I just recently realized that the drain having been unused may present an issue with vent gases being allowed into the house and nearby bedroom. Someone told me to just run water down the drain for about a minute (in case of leaks), then a 50/50 bleach solution for another minute, then clear water again. I don't know if this would be the recommendation here, and I am a bit worried that the drain having been unused may have dried out seals somewhere and cause a leak that it did not have before. There may be some "drain flies" that seem to point to the suspicion that the drain trap has dried out. This someone told me. I don't want to turn this into a further disaster. Any suggestions/corrections?