Why Your Spa Water Smells Like Rotten Eggs (And What to Do About It)

Jerry thought he was about to have the perfect Friday night.

He poured a glass of wine, slipped into his favorite swim trunks, pulled off the spa cover, and got ready to relax in his hot tub after a long week. But the moment he lifted the lid, he got hit with a smell so bad, it knocked him backwards.

It wasn’t chlorine. It wasn’t mildew. It smelled like rotten eggs—and the warm water wasn’t inviting anymore. Jerry slammed the spa cover back on, ran inside, and decided the couch was safer.

If your hot tub smells like sulfur, gym socks, or something died under the jets, don’t panic. You’re not alone, and your hot tub probably isn’t doomed. But that smell is trying to tell you something—and ignoring it could lead to cloudy water, foamy water, or even some expensive repairs.

Let’s break down why your spa water stinks and how to fix it.

What That Rotten Egg Smell Really Means

When spa water smells like rotten eggs, the most likely culprit is contaminated water.

That stink usually comes from sulfur-producing bacteria that thrive in warm, poorly treated water. These microbes multiply when the sanitizer level (like chlorine or bromine) is too low and the water isn’t circulated properly.

It can also happen when there's buildup in your filter compartment, jets, or pipes. That stagnant water gives bacteria time to throw a party—and no one wants to be invited.

Common Causes of Stinky Hot Tub Water

There are a few reasons that bacteria takes over your spa and makes the water smell bad. Let’s go through them:

Not Keeping Up with Daily Maintenance

Skipping a day here or there might not seem like a big deal—but in a hot tub, it adds up fast. Poor daily maintenance is one of the top reasons bacteria gets comfy in your spa.

Low Chlorine or Bromine Levels

If your chlorine levels or bromine levels drop too low, the bacteria you're supposed to be killing get a second wind. It’s like a gym with no staff—things get out of hand.

Dirty or Clogged Filters

If you haven’t cleaned your hot tub filters lately, they’re probably clogged with gunk. That limits water flow, traps bacteria, and leaves you with smelly water and cloudy water too.

Water That’s Been Sitting Too Long

Maybe you were on vacation or just forgot about it for a few weeks. That warm water just sitting under the spa cover becomes a hot soup of bacteria.

High Water Temperature

Keeping the water temperature cranked up too high without proper regular maintenance can speed up bacteria growth. That cozy hot water? Perfect for microbes if you’re not careful.

What to Do About It

Alright, enough about the problem—let’s talk about what to do.

Step 1: Open the Spa Cover and Let It Breathe

First things first—air it out. Lift the hot tub cover and give your spa some fresh air. That might reduce the strength of the odor right away. But don’t stop there.

Step 2: Check Chemical Levels

Use test strips to check your chemical levels, especially chlorine levels, bromine levels, and water balance. If the sanitizer is low, that’s your first clue.

Bring your sanitizer level back up where it needs to be—and shock the spa with extra sanitizer. That high dose will help kill off whatever has taken root.

Step 3: Clean or Replace the Filters

Dirty filters are like a wet sponge full of old soup. Rinse them with a hose and use filter cleaner if needed. If they’re past their prime, go ahead and replace them with clean filters. This step helps improve water flow and water quality right away.

Step 4: Drain and Refill if Needed

If the water still smells funky after shocking and cleaning, it may be time to pull the plug.

Use a garden hose to drain the water completely. Clean the hot tub surfaces with a cleaning solution, especially around the jets and inside the filter compartment. Then refill with fresh water and test everything again.

Step 5: Balance the Chemistry Like a Pro

Once it’s full, balance your calcium hardness, alkalinity, and pH for balanced water chemistry. This prevents future issues and keeps your hot tub in great shape.

Pro tip: Don’t just test once. Take water samples on a regular basis—weekly or even more often in heavy use periods.

Preventing the Smell From Coming Back

You don’t want Jerry’s Friday night fiasco to become your Saturday night disaster. Here’s how to keep your hot tub water clean and smelling fresh.

Maintain Water Balance on a Regular Basis

Balanced water keeps bacteria from growing and helps your hot tub chemicals do their job. Always keep an eye on chemical levels and pH.

Clean the Filters on a Regular Basis

Rinse weekly. Use filter cleaner monthly. Replace them every year or as needed. Clean filters = clean water.

Monitor Water Flow

Weak jets or bubbles that don’t feel right can be a sign of poor water flow. That usually ties back to dirty filters or pump issues—get them checked out before it turns into a costly repair.

Use the Right Sanitizer

Stick with either chlorine or bromine, and don’t switch back and forth. Keep your sanitizer level in the safe range and shock the water regularly.

Cover It, but Not Forever

Use a tight-fitting spa cover to keep out debris—but don’t trap moisture and bacteria. Let it air out once in a while to prevent buildup.

When It’s Time to Call in the Pros

If the smell keeps coming back or you’re tired of troubleshooting, it’s time for professional maintenance services. A technician can check the plumbing, flush out the system, and clean where your garden hose can’t reach.

Sometimes, the problem isn’t just the water—it’s the system behind it. Neglecting spa care for too long can lead to expensive repairs, or worse, a total system overhaul.

That’s where American Dream Pool & Spa Service comes in.

Keep Your Hot Tub a Place You Actually Want to Use

Your hot tub should smell like clean water and relaxation—not a sulfur-filled science experiment.

If your spa smells off, it’s time to act. Flush the system, fix the water, and commit to regular maintenance. And if you’re tired of fighting the stink every few months, we’re here to help.

American Dream Pool & Spa Service provides expert spa cleaning, hot tub maintenance, and repair for homeowners in Lincoln, Rocklin, Roseville, Granite Bay, Sheridan, Loomis, and Penryn. We’ll help you take the guesswork—and the rotten egg smell—out of your hot water routine.

Ready for a hot tub that smells like a spa, not a swamp?

Reach out today for spa and hot tub maintenance that actually works.

American Dream Pool and Spa Service is a trusted provider of pool and spa maintenance, repair, and cleaning services. They serve the areas of Lincoln, Rocklin, Roseville, Granite Bay, and Sheridan, CA, offering comprehensive care for both residential and commercial pools. Their services include everything from routine maintenance to specialized repairs for pool and spa equipment, ensuring that every pool owner enjoys a clean, safe, and well-maintained pool or spa throughout the year. With a focus on customer satisfaction, American Dream Pool and Spa Service strives to keep pools in top condition, regardless of the season.