Do I enter the new water heaters, toilets and plumbing for my rental property, in the asset improvement section?

[LenaH]

It depends. Generally, larger improvements like major plumbing must be depreciated over several years. But if an item isn't too costly (less than $2,500), you can typically write it off in full the year you bought it. 

• As per Table 1-1 below from Publication 527, a water heater would have to be capitalized. 
• Depending on the cost of the toilet installed in the rental property, it can be depreciated or written off as an expense under the de minimis safe harbor rule. For more information on the safe harbor rule, please see the information here. 
• The same concept would apply to the plumbing work. If the cost is relatively low and qualifies as a repair rather than an improvement, you can expense the cost. However, if the plumbing work was extensive, then it would have to be capitalized as an asset.