Rental Property Water Heater Depreciation: The 27.5-Year Rule

A water heater permanently installed in a residential rental property is depreciated straight-line over 27.5 years under MACRS, the same recovery period as the building itself. The IRS treats a plumbed-in water heater as part of the building’s plumbing system, which makes it a structural component rather than a five-year appliance. Rental property water heater depreciation follows the building, not the appliance schedule, and that single classification drives almost every other tax decision you’ll make about the unit.

The 27.5-Year Rule and Why It Applies

The tangible property regulations use a “unit of property” framework for buildings. The building structure is the unit of property, and the improvement analysis is applied separately to the structure and to eight building systems, one of which is plumbing.¹ A water heater connected to the building’s hot-water supply is part of the plumbing system, which makes it a structural component of the building.

Structural components inherit the building’s recovery period. For residential rental property, that period is 27.5 years under the general depreciation system.² A property qualifies as residential rental if at least 80% of its gross rental income for the year comes from dwelling units.³

The method is straight-line, meaning the cost is spread evenly across the recovery period. The first-year and final-year deductions are shortened by the mid-month convention, which treats the water heater as placed in service in the middle of the month you actually installed it.³ You report the deduction on Form 4562 and carry it through to Schedule E.⁴

The De Minimis Shortcut

Before you set up a 27.5-year depreciation schedule, check whether you can expense the whole thing instead. The de minimis safe harbor election lets landlords without an applicable financial statement immediately expense items costing $2,500 or less per invoice or per item.¹ Taxpayers who do have an applicable financial statement can use a $5,000 threshold.

The threshold is applied per unit when the invoice breaks out each item’s cost.⁵ A basic tank water heater installed by a plumber often runs past $2,500 once labor, delivery, and permits are added in, so many replacements won’t fit. But a modest DIY-purchase-and-plumber-install job under the limit can be expensed in full if you attach the election to your return.

Why It Isn’t Five-Year Property

The five-year MACRS class covers appliances placed in a rental unit like refrigerators, dishwashers, and window air conditioners.⁶ Those items can be unplugged and carried out without disturbing the building. A water heater bolted to the floor and hard-plumbed into the hot-water supply doesn’t pass that test. It moves with the plumbing system, not the tenant.

This is the most common mistake landlords make with water heaters. Seeing “appliances” on the five-year list and applying it to the water heater cuts the recovery period from 27.5 years to five, dramatically overstates the yearly deduction, and creates an underpayment. The IRS can impose an accuracy-related penalty of 20% on underpayments caused by negligence or disregard of the rules.⁷

Running the Numbers

Say you capitalize a water heater at $3,300, including the unit, installation, and permit, and place it in service in June. Divide $3,300 by 27.5 to get about $120 per full year. The mid-month convention treats June as half a month, giving you 6.5 months of depreciation in year one, or roughly $65. Every full year after that, you deduct $120. In the final year of the schedule, you claim whatever months remain.

The annual deduction is small on its own. But depreciation you claim (or were allowed to claim, whether you did or not) becomes subject to recapture when you sell the property, taxed at up to 25% on the recaptured portion. Getting the schedule right protects the deduction now and the gain calculation later.

When 39 Years or ADS 30 Years Applies

Two situations pull the water heater onto a different schedule.

If the building fails the 80% residential income test (say, a ground-floor retail space produces more than 20% of gross rents), the whole building is nonresidential real property and depreciates over 39 years.² Every structural component, including the water heater, follows the 39-year schedule.⁶

If you’re required or elect to use the Alternative Depreciation System, residential rental property placed in service after 2017 has a 30-year recovery period under ADS.³ The most common trigger is electing out of the Section 163(j) business interest limitation as a real property trade or business. That election lets you deduct more interest but slows depreciation on every real property asset, water heaters included.

Bonus Depreciation and Section 179 Don’t Apply

The One Big Beautiful Bill Act, signed in July 2025, permanently restored 100% bonus depreciation for qualified property acquired after January 19, 2025.⁸ Qualified property must have a MACRS recovery period of 20 years or less.⁶ At 27.5 years, a water heater doesn’t qualify.

Section 179 has the same problem. It applies to tangible personal property, which the IRS defines as property in or attached to a building other than structural components.⁶ A plumbed-in water heater is a structural component, so Section 179 is off the table too. A freestanding appliance in the unit can qualify. A built-in water heater cannot.

What Goes Into the Depreciable Basis

You depreciate the full acquisition cost, not just the sticker price of the unit. The IRS requires you to include the freight, installation, and testing costs needed to get the asset ready for use.⁹

For a typical replacement, capitalize:

The purchase price of the water heater
Delivery or freight charges
Plumber’s labor to install the unit
Municipal plumbing permit fees
State and local sales tax on the equipment

If you install the unit yourself, don’t add the value of your own labor. Unpaid labor cannot be included in the basis of property you construct or install.⁹

Don’t Forget the Old Unit

When you replace a water heater, the old one still has undepreciated basis sitting in your building’s schedule. The partial disposition election under Treasury Regulation Section 1.168(i)-8 lets you write off that remaining basis as an ordinary loss in the year of replacement.

Figure out what the old water heater originally cost (or estimate it using a reasonable method, such as a cost segregation study, if it came with the building), subtract the depreciation already claimed on it, and deduct the remainder. Report the loss on Form 4797 with “Partial Disposition Election” in the asset description.¹⁰

The election has a second benefit: the labor to remove and dispose of the old unit becomes a current-year expense rather than a cost added to the basis of the replacement. Without the election, the leftover basis of the old water heater keeps depreciating inside the building’s schedule until you sell the property, which can defer the loss for decades on an original-to-the-building unit.

Fixing Depreciation You Got Wrong Before

If you already put a water heater on a five-year schedule, missed depreciating one entirely, or used the wrong method, you generally can’t fix it with amended returns. The IRS treats it as an incorrect accounting method and directs you to Form 3115, Application for Change in Accounting Method.

For most depreciation corrections, this is an automatic change with no user fee and no advance IRS approval needed. Rev. Proc. 2015-13 sets the procedures, and Rev. Proc. 2024-23 lists the qualifying automatic changes.¹¹ You file Form 3115 with your current-year return, and all the missed or excess depreciation flows through a single Section 481(a) adjustment. If you underclaimed in prior years, that adjustment reduces this year’s taxable income.

The one narrow exception: a single year of incorrect depreciation can be fixed by amending that one return instead of filing Form 3115.

Records to Keep and for How Long

The IRS wants records supporting a depreciation deduction until the statute of limitations runs on the tax year in which you dispose of the asset in a taxable transaction.¹² For a water heater on a 27.5-year schedule, that’s the full depreciation period plus at least three years after the unit is retired or the property sold.

For each capitalized improvement, keep records showing the amount, the date placed in service, and the business purpose.⁶ In practice that means the purchase invoice, the installer’s receipt breaking out labor and permit costs, and something documenting the install date. If you take the partial disposition election on the old unit, hold onto the workpaper showing how you estimated its original cost too. When you eventually sell the property, you’ll need the full depreciation history to compute gain and recapture correctly.¹³

1
Internal Revenue Service. Tangible Property Final Regulations
2
Office of the Law Revision Counsel. 26 USC 168 – Accelerated Cost Recovery System
3
Internal Revenue Service. Publication 527 (2025), Residential Rental Property
4
Internal Revenue Service. 2025 Instructions for Form 4562
5
Internal Revenue Service. Increase in De Minimis Safe Harbor Limit for Taxpayers Without an Applicable Financial Statement Notice 2015-82
6
Internal Revenue Service. Publication 946 (2025), How To Depreciate Property
7
Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments
8
Internal Revenue Service. Treasury, IRS Issue Guidance on the Additional First Year Depreciation Deduction Amended as Part of the One Big Beautiful Bill
9
Internal Revenue Service. Publication 551, Basis of Assets
10
Internal Revenue Service. Instructions for Form 4797 (2025)
11
Internal Revenue Service. Revenue Procedure 2024-23 – Changes in Accounting Periods and Methods of Accounting
12
Internal Revenue Service. Publication 583, Starting a Business and Keeping Records
13
Internal Revenue Service. 2025 Instructions for Schedule E (Form 1040)