Why Getting Out of a Bathtub Is More Dangerous Than Getting In

That comparison comes from Table 2 of a study by Stevens, Haas, and Haileyesus published in the CDC’s Morbidity and Mortality Weekly Report (MMWR, June 2011). It remains the only nationally representative analysis of bathroom injuries in the United States, built from 3,339 emergency department records weighted to national estimates.

What does the data actually say?

The study coded what each person was doing at the moment they were hurt. Two of those categories are the same physical action in opposite directions:

• Getting out of the tub or shower: 23,055 injuries, 9.8 percent of the national total
• Getting into the tub or shower: 5,062 injuries, 2.2 percent

There is a coding detail worth knowing, because it makes the gap more meaningful rather than less. Slipping while bathing was coded as “slipped.” But slipping while getting into or out of the shower was coded as getting in or out, because the researchers considered those movements “a priori to be particularly hazardous.” So the getting-out figure already includes the slips that happened during it.

Why would the same step be more dangerous in one direction?

The report answers this itself, in its Editorial Note:

“Only 2% of injuries occurred while getting into the tub or shower, when bathroom fixtures and floors likely would be less slippery.”

Nothing about the architecture changes between the two trips. The tub wall is the same height on the way out as it was on the way in. What changes is everything else: the floor is wet, the tub is wet, the person is wet, and there is soap involved on both the feet and the hands that would otherwise steady them.

So the hazard is not really the height of the step. It is the step combined with what a shower does to every surface around it, including the two surfaces a person would use to catch themselves.

How does that fit the rest of the injury data?

It fits the largest categories in the study. Bathing or showering was the single biggest precipitating event at 27.5 percent. Slipping accounted for another 17.3 percent. The MMWR combines several of these into one summary figure:

“The precipitating events in 37.3% of injuries were bathing (excluding slipping while bathing), showering, or getting out of the tub or shower.”

The report’s own summary of the pattern is that “for all ages, the most hazardous activities were bathing, showering, or getting out of the tub or shower,” with roughly two thirds of all bathroom injuries occurring in the tub or shower itself.

Is there a written standard for the step?

There is, and it is far lower than most people expect. Section 608.7 of the 2010 ADA Standards for Accessible Design caps the threshold of a roll-in shower compartment at one half inch. In a transfer-type compartment, a threshold up to a half inch is permitted but has to be beveled, rounded, or vertical.

Section 303, which governs changes in level generally, sets out how that half inch has to behave:

• Up to 1/4 inch may be a vertical edge
• Between 1/4 inch and 1/2 inch must be beveled at a slope no steeper than 1:2
• Anything over 1/2 inch has to be ramped

The US Access Board’s guidance goes further than the minimum, noting that “trench drains and other designs that allow a flush transition to the shower floor will provide easier access,” and that a shower floor can slope up to 1:48 to control water without affecting accessibility.

Those numbers apply to public accommodations and commercial facilities. They do not apply to a private home, and no house has to meet them. They are useful anyway, because they are the only written American answer to the question “how big should the step be,” and the answer is measured in eighths of an inch.

A bathtub wall is not a half-inch step. We are not going to put a figure on the tub in a particular bathroom, because tub models vary and inferring a dimension from a manufacturer’s drawing is not the same as measuring one. The comparison stands without it.

What does RenewItHQ do about the step?

A low-threshold pan replaces the tub wall. That is the whole of it. The step-over is not softened or padded or made easier to negotiate; it is removed as a physical feature of the room, and what remains is a threshold in the range the written standard describes.

The rest of the room follows the same logic. A handheld on a hose means the water can be directed rather than stood under. A seat means standing for the length of a shower is a choice rather than a requirement. Three grab bars come on every shower we build, and blocking goes in behind the wall while the wall is still open, whether a bar is specified for that position on day one or not.

What we will not tell you

We will not tell you that any of this prevents a fall. The best available evidence on changing homes to reduce falls is a 2023 Cochrane review by Clemson and colleagues (Cochrane Database of Systematic Reviews, 2023), which looked at 22 studies and 8,463 people. It found home fall-hazard interventions reduced the rate of falls by 38 percent among people already at higher risk, and found no evidence of any reduction among people not selected for fall risk. Those interventions were assessments carried out by health professionals, mostly occupational therapists. None of them studied a walk-in shower.

So the honest description of what a low-threshold pan does is not a health outcome. It is a fact about the room: the step that 9.8 percent of bathroom injuries involve is no longer there.

Where the numbers come from

The injury figures are from Stevens JA, Haas EN, Haileyesus T, Nonfatal Bathroom Injuries Among Persons Aged ≥15 Years — United States, 2008, MMWR, June 10, 2011. Threshold and change-in-level requirements are from the 2010 ADA Standards for Accessible Design, sections 303 and 608.7, with additional guidance from the US Access Board’s guide to bathing rooms. The falls-intervention evidence is Clemson L et al., Cochrane Database of Systematic Reviews, 2023.