Bladder

The Bladder meter decreases naturally throughout the day, and can only be increased by going to the toilet. Upgrading to a better toilet can boost Comfort whilst the Sim is relieving him or herself. If a Sim's bladder starts to get full, they become extremely cranky; when it gets to the red, they make a wild dash for the toilet with urgency, and if they can't get there in time, the poor Sim causes an embarrassing accident on the floor, which will severely effect the Sim's Hygiene bar. Drinking a lot of coffee can make the Bladder meter decrease more rapidly. If a Sim does not flush the toilet, it can become clogged and will result in a mess that someone will have to clean up.

As a rule, community lots will have public toilets of some sort. In The Sims 2, Sims may occasionally have a fear or using a public toilet.

In The Sims 2, Outgoing and  messy Sims are also able to "use" shrubs and the AquaGreen Hydroponic Garden to relieve their bladder needs.