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 has an embarrassing accident on the floor, which will severely affect 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.

Sims have to train toddlers in order to let them use the potty by themselves. They will wet themselves if not potty trained. An older sim can click on the potty chair and potty train the toddler.

As a rule, community lots will have public toilets of some sort. In The Sims 2, Knowledge Sims and/or neat Sims may occasionally have a fear of using a public toilet. Having an accident is a fear on The Sims 2, and it takes away more influence than aspiration.

In The Sims 2, Outgoing and sloppy Sims are also able to "use" shrubs and the AquaGreen Hydroponic Gardento relieve their bladder needs. Sloppy Sims will also pee in the shower if their Bladder need is low enough. In The Sims 2: Pets Werewolves can use the Howl Interaction to Lower Non-Werewolves' Bladder Needs

In The Sims 3, the Steel Bladder Lifetime Reward makes it so that Sim who purchased it no longer has to use the bathroom again. In The Sims 3: World Adventures , Mummies do not have the Bladder Motive at all. Also the sim gains a moodlet for wetting themselves called "Embarrased" which gives -20 mood and makes hygiene 0%.

Trivia

 * The Sims Medieval features no Bladder meter. Instead, a Sim using a chamberpot gains a temporary buff.