Summary:

• When septic tanks become too full, they can crack, break, or overflow. Knowing how to spot the 6 most common warning signs can help you take action earlier.
• Strong odors, gurgling drains, and slow or clogged toilets are the earliest warning signs. Over time, this can progress to sewage backing up into your yard or home.
• Yearly inspections are the best way to identify problems like these before they escalate into disasters. Preventing issues is also more cost-effective and less stressful.

Do you remember the last time your septic tank was pumped out? If the answer is no, or it was over a decade ago, you’re long past due for a check-up, and early warning signs like bad odors and flooded yards are a strong indicator that you’re already experiencing trouble.

Problems like these can go from unpleasant to a total plumbing disaster in no time flat, so you never want to ignore them. Calling in a licensed plumber who knows how to inspect the tank to see whether it’s full and pump it out can help you avoid more costly repairs later on.

Below, we’ll explain the top six warning signs that it’s time to empty your septic tank and what you can do about it. Read on to learn them—then contact us to get reliable service fast.

Six Signs Your Septic Tank Is Full

Contrary to popular belief, a septic tank that’s too full won’t always be immediately obvious from above the ground. All six of the most common warning signs are easy to confuse with other plumbing problems and may even seem harmless at first.

1. Strong Odors

A little odor after bathroom use is pretty normal, but it should clear away quickly and not come back in between visits on its own. If it sticks around or is so overwhelming that it makes you feel sick, chances are your septic tank is involved.

Be on the lookout for:

• Sulfurous or rotten egg smells near the tank or the drain field
• A strong, musty, or damp smell near the drains in your home
• Odors that seem worse after heavy rain or in specific areas of the yard
• Bad smells that seem to get worse when you open a window

Septic-related odors happen because human waste produces methane and a variety of other noxious gases as it breaks down. A healthy septic tank has plenty of room to accommodate these gases, but they can start to leak out into your home or yard if it’s too full.

2. Gurgling in the Plumbing

If you don’t smell anything, you may hear something. Gurgling noises in your drains and pipes are a red flag that clogs are forming in the line, and an overly full septic tank will increase your risk of a clog more and more over time.

Be on the lookout for:

• Loud gurgling or bubbling sounds when flushing toilets
• Noisy sink, dishwasher, laundry, or bathtub drains
• Air burps that bubble up when the sink or bowl is full
• Greatly delayed draining from tubs and showers

These noises happen when waste and gases can no longer move freely throughout your system. Instead of escaping out of your roof vent or staying in your tank, they look for the path of least resistance to relieve the pressure, which is usually the drains in your home.

3. Slow or Clogged Toilets

Toilets that flush slowly, refuse to flush at all, or make a lot of noise are often the first red flag for septic tank problems. Waste is designed to travel directly from your toilet bowl into the tank, so if it has nowhere to go, it may seem like you have a clog.

Watch for these warning signs:

• Weak or sluggish flushing that doesn’t clear the bowl
• Bubbling or gurgling sounds while you flush or after
• Flooding that reaches the top of the bowl—or worse, overflows the edge  

It’s impossible to tell if problems like these are related to a simple clog or a more serious problem like a cracked or overflowing tank unless you have the right equipment. We have special technology that can help us diagnose the problem from above the ground.

Read More: Common Septic Tank Repairs and What They Cost to Fix

4. Pooling Water in Your Yard

Standing water in your yard is never normal, but it’s especially suspicious when it crops up near the site of your septic tank and isn’t directly related to recent rain. When the tank gets too full, excess waste can spill out above it and turn your yard to a soggy mess.

Look for problems like these:

• Large pools of water that aren’t related to local flooding
• Muddy, mucky soil directly above the tank itself or the drain field
• Standing water that smells foul, like a swamp or rotting garbage

This is another pressure-related issue where too little room in the tank directly contributes to sewage backups. There’s very little you can do to fix this on your own at home, and sewage exposure can be a health hazard, so reach out to a plumber for help right away.

Read More: What to Do During a Plumbing Emergency

5. Faster-Growing Grass

It’s very easy to look at thick, lush grass as a net positive—until you realize that waste is a really effective fertilizer. Plants love the micronutrients and minerals in sewage, so even a minor leak can make them grow bigger, stronger, and healthier near the tank.

Keep a close, watchful eye out for:

• A bright green patch of grass directly above the septic tank
• Thicker or taller grass near the tank or the drain field
• Unusual growth patterns that return even after you mow
• Mushrooms that crop up in one specific area of the yard

Signs like these often show up long before it’s obvious that you have a problem with your septic tank, and they’re almost always overlooked at first. It’s a little less suspicious if your entire lawn is equally lush and vibrant, but still in the realm of possibility on smaller plots.

6. Sewage Backups

This is the worst-case scenario—and the ultimate outcome from every other warning sign on this list. If your septic tank is completely full or in need of repair, wastewater can and will start backing up into your drains, sinks, toilets, tubs, or basement.

Look for warning signs like:

• Cloudy, grey, brown, or black water filled with debris
• Water that very obviously smells like human waste
• Strange insect activity (e.g., fly eggs or maggots nearby)
• Damp or wet floors paired with a strong sewage smell

If you have any reason to suspect a backup, don’t try to clean the mess yourself or drink the water in your taps, as it may be contaminated. A healthy septic tank is loaded with bacteria like E. coli, Giardia, Salmonella, and other pathogens that can make you very sick.

Book Your Septic Tank Service with Caccia Now

With septic tanks, prevention is always better than the cure—and typically far less expensive, too. Having your plumbing system and septic tank inspected every year makes it easy to spot when the levels are getting too high, so you can have the greywater pumped out. 

If you suspect you have a full septic tank now, or you need assistance with any other plumbing problem, there’s an easy and effective way to get help fast. Call Caccia Home Services at (650) 442-1470 and we’ll get someone out to you right away.

Frequently Asked Questions About Septic Tanks

1. How long should my septic tank last?

Most septic tanks here in California are designed to last 50+ years with proper maintenance, but you can’t “set it and forget it.” Ignoring the system until you start experiencing problems is a recipe for disaster later on down the road. 

Scheduling a yearly inspection will always be the best way to keep your tank in good condition. It’s also a great way to spot high sewage levels early.

2. Why do septic tanks fail?

The answer depends on the type of “failure” you experience. Septic tanks can “fail” in two main ways:

• Biological failures happen when the natural bacteria that break down waste die off suddenly or are killed off by substances entering the system.
• Physical failures occur when the tank walls, lid, pipes, or internal components like baffles crack or break.

For biological die-off, the main cause is usually chemical cleaners, bleach, or medications like antibiotics that enter the system. For physical breakage, the main causes include wear and tear, earthquakes, and accidents related to excavation. Always make sure you know where your septic tank is located before you dig!

3. Can sewage really enter my drinking water?

Unfortunately, yes—sewage contamination is possible, and it isn’t always obvious until it’s too late. Typically, this is a side effect of a leak or minor sewage backup, but it can also be related to pressure changes in your pipes or problems with the local water supply. Backflow testing can help confirm that your water is safe to drink and stays that way.