ADU toilet leak - can landlord deduct from security deposit?

Disclaimer: The question below was submitted by a reader. Names have been anonymized. The information provided is for general informational purposes only and does not constitute legal, financial, or professional advice. Individual circumstances vary, and readers should contact their service provider directly or consult a qualified professional for advice specific to their situation.

Randy, California April 19, 2025

My son rented an ADU (California) and in the lease it indicated that the landlord will pay the water bill. The water bill was one bill tied to both the main primary house where the landlord lives and the ADU which is where my son lived and rented from the landlord. For a couple months the toilet in the ADU apparently had a small leak from the flapper and my son being only 22 and on his own for the first time not knowing water was leaking. The landlord eventually repaired/replaced the flapper in the toilet. When my son eventually moved out the landlord took $250 from his security deposit because he said his water bill was $500 more than normal and so he would split the loss and said my son should have known about the leak and tell the landlord to fix! First off to just do this and split the loss doesn't make sense because the primary house is WAY larger than the ADU and there are 4 people living in the house versus my son living in the ADU and so how does he know there is no leak elsewhere and/or just his family using more water! Plus again how is my son supposed to know if there is a leak of not especially since it's not like there was visable water leaking! I just think this is not legal

ConnectCalifornia followed up with Randy requesting more information

ConnectCalifornia Expert April 19, 2025

Hi Randy, thanks for reaching out. This is a frustrating situation, and you raise some valid concerns. To give you the best guidance, could you clarify a few things? Does the lease specifically say the landlord is responsible for water, and did the landlord provide any documentation of the water bills showing the $500 increase? Also, did your son receive the itemized security deposit deduction statement that California law requires?

Randy, California April 20, 2025

Yes the lease clearly states landlord pays water. He did get an itemized statement but it just says 'water bill overage - tenant portion $250.' No actual water bills attached. And honestly, the toilet wasn't making any noise or anything visible - how was a 22 year old supposed to know there was a silent leak inside the tank? The landlord only found it during a routine inspection.

ConnectCalifornia Expert April 21, 2025

This doesn’t sit right. If the lease says the landlord pays water, then the landlord pays water - they can’t suddenly change the rules because a bill came in higher than expected.

Here’s the thing: a toilet flapper leak isn’t tenant damage. It’s a maintenance issue. Under California Civil Code 1941, keeping the plumbing in working order is the landlord’s job. Your son couldn’t reasonably have known about a silent leak that wasn’t causing any visible water on the floor. And with four people plus regular water use in the main house, the landlord has no way to prove the extra usage was all from the ADU anyway.

Security deposit deductions are supposed to cover damage beyond normal wear - not routine maintenance repairs the landlord should have caught themselves.

I’d send a written demand letter asking for that $250 back. Keep a copy. If the landlord refuses, small claims court is a real option here (filing fee runs $30-75). Bring the lease showing who pays water, and any texts or emails about when the flapper was reported and fixed.

Outcome: Pending

Awaiting follow-up from reader on whether they pursued small claims court.

Updated April 22, 2025

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