Shower Temperature Fluctuates? Why Your Water Goes Hot and Cold (South Florida Guide)

Nathanael Jolteus • December 15, 2025

If your shower temperature fluctuates, suddenly turning hot, then cold, then hot again, you’re not alone.


This is a common and frustrating problem for homeowners, and in some cases, it can even be dangerous, especially for children and older adults.


In South Florida homes, temperature swings are often caused by aging shower valves, water pressure changes, or problems inside the hot water system.


Let’s break down what’s actually causing it and how to fix it.


1. Failing Shower Mixing Valve (Most Common Cause)

Your shower uses a mixing valve to balance hot and cold water.


When the valve wears out:

  • it can’t maintain consistent temperature

  • pressure changes affect temperature

  • hot water surges unexpectedly

  • cold water suddenly dominates

Older valves (especially pre-1990s) are very prone to failure.


2. Someone Uses Water Elsewhere in the House

If your shower temperature changes when:

  • a toilet flushes

  • a sink turns on

  • the washing machine starts

…it usually means your plumbing system isn’t pressure-balanced.


Modern pressure-balancing valves prevent this. Older systems do not.


3. Water Heater Issues

Temperature fluctuations can also originate at the water heater.


Common heater-related causes:

  • sediment buildup reducing heat consistency

  • failing thermostat

  • undersized water heater

  • heating element cycling improperly

In South Florida, mineral-heavy water causes sediment to build up quickly, making this more common.


4. Low or Fluctuating Water Pressure

Changes in pressure affect how much hot vs cold water reaches the shower.


Causes include:

  • failing pressure reducing valve (PRV)

  • partially closed shutoff valves

  • pipe restrictions from corrosion

  • municipal pressure changes

Pressure problems often show up first in showers.


5. Tankless Water Heater Limitations

If you have a tankless system, temperature swings can happen when:


  • flow rate is too low

  • multiple fixtures run at once

  • the unit is scaled internally

  • sensors misread demand

Tankless systems require proper sizing and regular maintenance.


6. Why This Is a Safety Issue

Sudden temperature changes can cause:

  • scalding

  • slips and falls

  • burns

  • discomfort and stress

Children and seniors are especially vulnerable.


If water suddenly turns very hot, it should be addressed immediately.


7. Why This Happens More in South Florida

South Florida homes often have:


  • older plumbing systems

  • aging shower valves

  • mineral-heavy water

  • higher water pressure

  • fast sediment buildup in heaters

All of these contribute to unstable shower temperatures.


8. DIY Checks You Can Do

You can test:


✔ whether temperature changes when other fixtures run

✔ hot vs cold pressure at other sinks

✔ age of the shower valve

✔ age of the water heater


If the issue is consistent, it’s not user error.


9. Why Adjusting the Handle Doesn’t Fix It

Turning the handle back and forth only masks the problem temporarily.


If the valve internals are worn, temperature instability will continue, and often worsen over time.


10. When to Call a Plumber

Call a professional if:

  • temperature swings happen daily

  • water suddenly turns very hot

  • multiple showers are affected

  • the home has older plumbing

  • the water heater is 8+ years old

  • pressure changes occur throughout the house

These indicate system-level issues.


11. What We Do (Professional Solution)

At Leading Plumbing Services, we:

  • inspect shower valves

  • test pressure balance

  • replace failing mixing valves

  • inspect water heater performance

  • flush sediment buildup

  • test pressure regulation

  • restore safe, consistent temperature

We fix the cause , not just the symptom.


12. Long-Term Prevention

To prevent future temperature swings:


✔ upgrade to pressure-balancing valves

✔ maintain your water heater yearly

✔ address pressure issues early

✔ replace aging plumbing components


Preventive upgrades improve comfort and safety.


Final Thoughts

If your shower temperature fluctuates, it’s a sign your plumbing system can’t properly balance hot and cold water.


Fixing it early:

  • improves comfort

  • prevents scalding

  • protects your plumbing

  • avoids emergency repairs

Call/Text us today for shower temperature diagnostics and repair:


(561) 506-6159

The Little Valve Under Your Sink Is Leaking. Here's When to Worry

By Nathanael Jolteus • September 5, 2026
You reach under the sink for something and notice a puddle. Then you see it: water collecting around the small shutoff valve coming out of the wall. It may only be dripping now, but a leaking shutoff valve, also called an angle stop, deserves attention because it's connected directly to your home's pressurized water supply. Here's what to do. FIRST: Figure Out How Serious the Leak Is A few drops around the valve stem is different from water spraying from the connection. If it's actively spraying or the leak is getting worse: -Stop using the fixture. -Put a container or towels underneath if safe. -Don't repeatedly open and close an old or corroded valve. -Shut off the home's main water supply if you cannot control the leak locally. If water is reaching an electrical outlet or appliance, keep away from affected area and address the electrical hazard safely. WHY Do Shutoff Valves Start Leaking? These valves can sit untouched for years. Then one day they're operated and suddenly begin dripping. Possible causes include: A worn valve stem or seal. Internal components deteriorate with age. A leaking connection. Water may be escaping where the valve connects to the supply pipe or fixture supply line. Corrosion. An older valve or connection can weaken enough to begin leaking. A failing supply line nearby. Sometimes the valve isn't actually the source. Water from the flexible supply line above it runs downward and makes the valve appear responsible. That last possbility is why finding the exact leak point matters. When Is This an Emergency? Call a plumber promptly if: -water is spraying instead of dripping -the valve won't completely shut off; - the valve looks heavily corroded; -the leak suddenly becomes worse; -the wall or cabinet is getting wet; -the connected supply line is bulging or damaged; or - you can't stop the water A slow drip may not require a middle-of-the-night response, but it shouldn't be forgotten either. Water leaking inside a cabinet can damage wood, drywall and flooring before the problem looks serious from the outside. DON'T DO THIS If an old valve feels stuck, don't put excessive force on it with pliers. The goal is to stop a leak, not turn an aging valve or connection into a broken pressurized line. If you're unsure, isolate the home's water supply and have the valve inspected. A Small Part Can Still Cause a Big Mess Shutoff Valves are easy to overlook because they're small. But they're also supposed to be your first line of defense when a toilet, faucet or appliance develops a leak. If the shutoff itself doesn't work when you need it, you lose that protection. That's a good reason to repair a leaking or unreliable valve before the next plumbing problem happens. Need a Plumber for a Leaking Shutoff Valve in South Florida? Leading Plumbing Services can identify whether the leak is coming from the valve, connection or supply line and repair the actual source. Call or text Leading Plumbing Services @ 561 506 6159 If water is actively escaping and the fixture valve won't stop it, shut off the main water supply if you can safely do so and get plumbing help as soon as possible. Author: Nathanael Jolteus

Shower Won't Turn Off? Here's What To Do Before the Bathroom Floods

By Nathanael Jolteus • September 4, 2026
You turn the shower handle to OFF. The water keeps running. You try it again. Nothing. Ugh so annoying. If your shower won't turn off, don't keep forcing the handle. A failed cartridge, valve , or internal component may be preventing the water from shutting off, and a small repair can become a much bigger problem if something breaks behind the wall. Here's what to do. FIRST: STOP the Water If the shower is running normally into an open drain, you have a little time. But you still want to stop the flow as soon as possible. If you know where your home's main water shut off valve is, turn it off. Then: - Keep the shower drain clear -Move anything that could block the drain. -Don't remove the shower handle or valve while the water is still on. -Don't force a stuck handle with tools. If water is escaping outside the shower or entering a wall, treat it as an active plumbing emergency. Why Won't the Shower Shut OFF? Usually , the problem is inside the shower valve. Common possibilities include: A failed cartridge. The cartridge controls water flow and temperature. When it wears out or breaks, turning the handle may no longer stop the water. A damage valve stem or internal component. The handle can move normally while the parts behind it no longer respond correctly. Mineral buildup. Deposits can interfere with moving components and make an aging valve harder to operate. A broken handle connection. Sometimes the handle turns, but it isn't actually moving the valve mechanism behind the wall. The important part: don't assume you need to replace the entire shower valve until the problem has been properly diagnosed. When Should You Call an Emergency Plumber? Get help quickly if: - the shower is running at full flow and won't stop - the main shutoff doesn't work; -the water is leaking from behind the handle or wall; - the shower is overflowing because the drain can't keep up; -you hear water running inside the wall; or - shutting off the shower affects the rest of the plumbing unexpectedly. If the water is safely draining, you may have time to arrange a repair, but leaving the shower running wastes water and puts unnecessary stress on the situation. ONE Mistake to Avoid Don't start taking the valve apart while the plumbing is pressurized. Removing the wrong component with the water supply is still on can turn a shower that won't shut off into water spraying directly from the wall. Get the water isolated first. Diagnose second. Need Help With a Shower That Won't Turn Off in South Florida? A shower that keep running is frustrating, but the solution may be relatively straightforward when it's handled before additional damage occurs. Leading Plumbing Services LLC can diagnose the valve, determine what actually failed, and make the appropriate repair. Call or text Leading Plumbing Services: 561 506 6159 If water is actively escaping into the bathroom, wall or surrounding rooms, shut off the home's water supply if you can safely do so and get plumbing help right away. Author: Nathanael Jolteus