Feces, urine and sweat—just how gross are hot tubs?

If we've talked to you about using your new home as a vacation rental, we warned against having or marketing that you have a hot tub.  There's a lot of liability, as they can be pretty filthy environments when used repeatedly by guests.  And there's nobody there to treat them chemically during a guest's stay, so they get very unhealthy, very quickly.  That's only part of it.  Another big issue regarding liability is that any time you have standing water, you run the risk of drowning by small children.  And with people on vacation and likely drinking, everyone's guard is down.  Our recommendation is that if you plan to get a hot tub, take the following precautions:

1) Lock it up securely

2) Don't advertise it with your vacation rental

3) If guests arrive and ask to use it, simply say "It's out of order which is why we didn't advertise it."  You can also just say, we don't share it for liability reasons. 

4) When you or family and friends use it, be sure to follow guidelines in treating it after each use.

The health factors present a big threat.  Here's a microbiologist's take on hot tubs.

Bacteria, viruses and fungi.

When we enter the waters of a Jacuzzi whatever we have on our skin we deposit into the warm water swirling around us. This includes the 100mg or so of feces that is usually present between our buttock cheeks. This means that while you're relaxing in the warm water, you'll likely breathe in or swallow your Jacuzzi partner's body's bacteria, viruses and fungi.

The more people in the Jacuzzi, the higher the levels of feces and sweat shed into the water (and urine if anyone has peed in the water). And these bodily deposits can be used by the bacteria as direct nutrients.

For microbiological safety, most Jacuzzis that recirculate water have microbe-removing filters and water is treated with microbicides (which kill germs) such as chlorine, bromine, or other disinfectants to control bacterial numbers.  Such chemicals are toxic and cause skin and eye irritation. This is why Jacuzzi users are advised to shower after bathing (and should also shower before, too).

The temperature of the water within a Jacuzzi (around 104°F or 40°C can also cause potentially serious health problems such as core overheating which can lead to feeling faint or even loss of consciousness and potentially drowning.  This is especially the case for children and pregnant women, along with people with underlying health conditions, who should always check with their GP before using a Jacuzzi. This is why most sessions are advised to last no more than around 15 minutes and should be supervised.

Dirty or filthy?

While personal Jacuzzis may be relatively safe microbiologically, public (hotel or spa) Jacuzzis can potentially be very high in infection-causing bacteria (germs), particularly if water is recycled.  The root problem is poor public compliance with personal hygiene guidelines and inadequate water treatment maintenance. Improperly maintained public Jacuzzis can lead to outbreaks of infections by human-associated bacteria which survive well in water.

These include E.coli, Staphylococcus aureus, Pseudomonas aeruginosa and Legionella pneumoniae. These Jacuzzi pathogens can cause gut infections, diarrhea, septicemia, skin infections, urinary tract infections and respiratory infections, including Legionnaires' disease.

Legionella bacteria are particularly found in the water droplets within the Jacuzzi steam and inhaling the contaminated steam could lead to the development of life-threatening pneumonia.  Indeed, the infection risk from Jacuzzis is so significant that in the US, the Centers for Disease Control has released official advice on how to prevent this.

So if you do still want to enjoy a hot tub or a Jacuzzi, is there a way of telling if it's safe or not? There are some clear signs of a germ-filled Jacuzzi. When urine and other body fluids such as sweat mixes with the chlorine used to disinfect Jacuzzi waters it creates an irritant, a pungent chemical called chloramine, which is what causes sore eyes when swimming in public pools.  The more bathers that deposit their bodily fluids the stronger the smell of the chloramine (which smells a bit like bleach) and the greater the likelihood that the spa or hotel Jacuzzi has low levels of disinfectant and high levels of bacteria. So if the Jacuzzi is strong smelling, the chances are it may be unsafe to use—even if the waters look clean and clear.