Swimming pools are a haven for relaxation, social gatherings, and exercise. But to keep your pool inviting and safe, maintaining clean and balanced water is essential. One of the most effective ways to ensure a healthy pool environment is to know what not to put in a pool. From harmful chemicals to everyday items that seem harmless, you may be unknowingly compromising water quality and swimmer safety.
In this article, we’ll explore in-depth the harmful substances and everyday objects you should avoid putting in your pool to protect equipment, maintain water balance, and ensure a safe swimming experience for everyone.
Why It’s Important to Avoid Introducing Foreign Substances
Your pool’s water chemistry must remain in balance to prevent algae growth, bacterial contamination, and damage to pool surfaces and equipment. Adding the wrong items to your pool—either intentionally or unintentionally—can throw off this delicate balance, leading to costly repairs and health hazards.
Some pool contaminants may react dangerously with chlorine and other sanitizers, while others may clog filters, degrade equipment, or harm swimmers’ skin and eyes.
Let’s explore the items you should never put in a pool.
1. Household Cleaning Products (Except Pool-Specific Ones)
Many people believe they can use household disinfectants or cleaning agents in place of pool chemicals to save money or handle emergencies. This is a serious mistake.
Why It’s Hazardous
Products such as laundry detergent, all-purpose cleaners, or even vinegar are not formulated for pool use. They often contain ingredients that:
- Disrupt pH balance
- Produce foam or cloudy water
- React with chlorine to form harmful gases
For example, mixing bleach with acid-based cleaners can produce chlorine gas, which is toxic when inhaled.
Correct Pool Cleaning Products
Instead of using household products, always opt for pool-certified chemicals such as:
- Pool shock (calcium hypochlorite or sodium dichlor)
- Algaecides designed for your specific pool type
- pH balancers (soda ash, muriatic acid)
These are formulated to work safely with your pool’s ecosystem.
2. Oil-Based Products (Shampoos, Soaps, Lotions)
Before diving in, swimmers often bring oils, soaps, and lotions with them—many of which end up rinsing off in the pool.
The Problem with Oils
Oil-based products can:
- Coat pool filters and reduce their efficiency
- Create a slick surface on the pool walls and floor
- Deplete the free chlorine in your water
These residues can irritate swimmers and contribute to water imbalances.
Recommended Practice
To protect your pool water:
Encourage swimmers to shower before entering the pool and avoid using oil-based skin products immediately before swimming.
3. Fertilizers (Even if Nearby)
Fertilizers used on nearby lawns or gardens can be washed into the pool by rain or wind.
Dangerous Consequences
Fertilizers often contain:
- Phosphates, which act as a food source for algae
- Nitrogen and potassium, which throw off chemical balance
- Pesticides that may harm sensitive skin
Prevention Strategies
To keep fertilizers out:
- Avoid overwatering nearby lawns after fertilizing
- Install barriers or redirect runoff water
Also, consider using phosphate removers regularly, especially during warm months when algae growth is common.
4. Debris That Can Clog the Filter
Leaves, grass clippings, dirt, and insects are common pool invaders. While they naturally fall into the water, large quantities can overwhelm a pool’s filtration system.
What Happens When Debris Overloads the Pool
Too much organic debris leads to:
- Blocked skimmer baskets and filters
- Increase in organic matter that needs chlorine
- Possible discoloration and staining of pool surfaces
How to Protect Your Pool
Implement a regular skimming and vacuuming schedule. Cover the pool when not in use to reduce the amount of debris that gets in. Use a leaf rake or mesh net to remove large leaves and twigs before they sink to the bottom.
5. Paints, Thinners, or Solvents
Painting nearby surfaces or fixing maintenance issues can be tempting to do around the pool area. However, dripping paint or thinners into the pool—even accidentally—can be problematic.
Why These Are Damaging
These chemicals:
- Can float on top of water, creating a persistent oily film
- Are typically resistant to chlorine breakdown
- Can lead to toxic chemical cloud formation when mixed with pool water
Safer Painting Practices
If painting near the pool, always:
- Use brushes instead of sprayers
- Ensure cans are covered and away from the pool edge
- Clean up spills immediately and thoroughly
Better yet, perform painting tasks on dry, windless days and away from the pool as much as possible.
6. Food and Drinks
It’s common to relax by the pool with snacks and beverages, but if these items end up in the water, they can cause issues.
The Hidden Risk of Poolside Food
Food residues such as:
- Grease from hamburgers or fried foods
- Sugary drinks that attract insects and bacteria
- Oil from chips or nuts
…can contribute to water clouding or foaming.
Managing Food Near the Pool
Set a designated area for food consumption. Use covers for drinks to prevent spills, and encourage guests to clean as they go to minimize contamination.
7. Garbage and Trash
Items like plastic wrappers, paper, and Styrofoam often end up floating in the pool due to improper disposal.
Why Littering in the Pool is a Big Deal
These items not only look unsightly but:
- Can block skim valves or pump intakes
- May begin to degrade and stain surfaces
- Attract bugs and bacteria to the pool perimeter
Maintaining a Clean Pool Environment
Place accessible trash bins around the pool area. If children are present, use bins with secured lids. As part of your pool maintenance routine, perform a quick visual check for floating garbage several times a day.
8. Sunscreen (Careful Use Required)
Sunscreen is essential for protecting skin from UV damage. However, oil-based or non-water-soluble sunscreens can impact pool chemistry.
Understanding the Impact
Sunscreen:
- Can leave a film on the water surface
- May contain chemicals that combine with chlorine
- Increases in chemical usage when many people are using it
Choosing the Right Sunscreen
Opt for water-soluble or reef-safe sunscreens that are less harmful to the pool water. Encourage guests to apply sunscreen at least 15 minutes before entering the water to allow it to absorb into the skin.
9. Pets and Other Animals
While dogs, cats, or other pets might enjoy the water, their presence brings in contaminants from soil, fleas, and their own bodily fluids.
Contaminants from Animals
Pet-related issues include:
- Introducing fecal matter that can contain parasites like Cryptosporidium
- Spreading oils and fur in the pool water
- Disrupting the filter system when they shake off
Managing Pets Around the Pool
If pets use the pool:
- Restrict their access unless under supervision
- Rinse pets with fresh water before and after swimming
- Increase filter run time after pet use
Also, have a backup plan in case of an accident, like a pet-safe disinfectant or enzyme-based water clarifier.
10. Metals That Cause Staining
Metal objects like coins, garden tools, or even pool maintenance equipment can leave behind rust or cause staining when submerged in water too long.
Common Sources of Metal Contamination
- Metal pool toys
- BBQ utensils left near the edge
- Iron in the water supply (if unfiltered)
How to Prevent Metal Staining
Use a metal sequestrant or chelating agent as part of your chemical routine, especially if your tap water has high iron content. Remove any metal items from the pool immediately upon discovery, and rinse metal pool accessories regularly.
11. Pesticides and Herbicides
Spraying the garden near your pool may seem harmless, but wind or rain can carry pesticides into the water.
Effects of Pesticides in Pool Water
Pesticides typically:
- Contain harsh chemicals that react with chlorine
- May kill algae but can also damage beneficial organisms and irritate skin
- Pollute water to the point where it must be partially or fully drained
Safe Pest Control Practices
Avoid spraying directly near the pool, especially in the direction of water. Read pesticide labels for wind drift warnings and apply products after sunset when outdoor activity is lower.
12. Chlorine and Pool Chemical Compatibilities
While pool chemicals are necessary, mixing incompatible substances can create unsafe conditions.
Common Chemical Combinations to Avoid
- Chlorine + Muriatic acid (can release toxic chlorine gas)
- Chlorine + Ammonia (produces nitrogen trichloride, a strong irritant)
- Calcium hypochlorite + Algaecides (some may cause chemical reactions)
Chemical Handling Best Practices
Always:
- Store chemicals in a dry, cool, and accessible area separate from each other
- Add chemicals only as directed, never more than the pool requires
- Test water regularly with a test kit before and after chemical application
13. Swimming Diapers and Soiled Clothing
Although swim diapers are designed for children, they are not completely leak-proof. In addition, soiled bathing suits or swimwear should not be allowed in the pool.
Risks of Contamination
These items may introduce:
- Bacteria like E. coli or Cryptosporidium
- Excess organic matter requiring a higher chlorine demand
- Solid particles that can clog filters or settle as sludge
Hygiene Practices Around the Pool
Encourage children to wear layered swimwear (tight-fitting wet suits over swim diapers), and have scheduled bathroom breaks. Provide rinse showers before entry, and change soiled swim diapers away from the poolside.
14. Painted or Sealed Playthings
Inflatable toys, beach balls, or pool floats can enhance your pool experience—but many are painted, sealed, or have stickers.
Hidden Toxins and Dyes
These items may:
- Release dyes or paint into the water
- Have finishes that contain oil or lacquers
- Break down faster when immersed and exposed to UV and chlorine
Safe Toy Selection Tips
Choose toys labeled as “pool-safe” or from reputable brands that test for chlorine resistance. Rinse toys before and after use, and avoid colored inflatables that lack proper chemicals seals.
15. Human and Animal Waste (Including Pee and Vomit)
This may sound obvious, but human waste—including urine—can significantly affect pool water quality.
Why Even Pee Can Be Harmful
Urine:
- Contains ammonia
- When mixed with chlorine, forms chloramines that irritate eyes and skin
- Increases demand on sanitizers, leaving less protection
Vomit can introduce pathogens like norovirus and bacteria that may survive even in chlorinated water.
What to Do When Contamination Occurs
Drain and thoroughly disinfect the pool if:
- Vomit or fecal accidents occur
- Multiple people complain of irritated skin or eyes after pool use
- Chlorine levels fall below 1–3 ppm even after shocking
Conclusion: Keep Your Pool Clean by Knowing What Not to Put in It
Maintaining a clean and healthy swimming pool requires more than just regular chemical treatment—it also involves being mindful of what goes into your pool. Avoiding harmful substances and inappropriate items plays a significant role in:
- Protecting swimmer health
- Preserving pool equipment
- Ensuring optimal water clarity and balance
By following these guidelines on what not to put in a pool, you can extend the lifespan of your investment, reduce maintenance costs, and provide a cleaner, safer experience for everyone who uses it.
So, the next time someone asks whether that bottle of shampoo, toy, or paint can go near the pool, you’ll know the risks—and how to prevent them.
Additional Tips for Pool Owners
- Invest in a high-quality pool cover for off-season storage
- Test water chemistry at least twice a week, more frequently during peak use
- Educate guests on pool-friendly behaviors before gatherings
Stay proactive and vigilant, and your pool will remain a source of joy and comfort for many years.
Remember, what you keep out of your pool is just as important as what you put into it.
Can I use household cleaners to scrub my pool tiles or walls?
Using household cleaners to scrub pool tiles or walls is not recommended. Many common cleaning products contain chemicals that are not compatible with pool water chemistry and can disrupt the balance of chlorine and pH levels. Additionally, some ingredients may leave behind residues that are harmful to swimmers or can damage the pool’s surface over time.
Instead, it’s best to use pool-specific cleaning products or a mixture of water and muriatic acid (diluted properly and used with caution) for tough stains. Always scrub with a non-abrasive brush to avoid scratching tile surfaces and follow up with proper filtration to remove any leftover debris or cleaning agents. This ensures a safe and clean environment for pool users.
Is it safe to add bleach to my pool for disinfection?
While bleach does contain sodium hypochlorite, which is a form of chlorine, not all bleach products are suitable for pool use. Some household bleaches include fragrances, stabilizers, or other additives that can cloud the water or irritate the skin and eyes. It’s crucial to check the label and ensure that the primary active ingredient is only sodium hypochlorite without additional chemicals.
If opting to use bleach, it must be unscented and free of thickeners or_colors. Also, the dosage must be accurate based on your pool’s volume and existing chlorine levels. However, for consistent and reliable disinfection, it’s best to use pool-grade chlorine products specifically formulated for swimming pools.
Can I pour algaecide directly into the skimmer?
Pouring algaecide directly into the skimmer is generally not recommended. The skimmer draws water from the surface and sends it through the pump and filter system, but applying algaecide this way can cause it to be overly concentrated in the filter or heater before it disperses properly. This can potentially damage equipment or reduce the effectiveness of the treatment.
The correct method is to dilute the algaecide in a bucket of water and then pour it evenly around the perimeter of the pool while the pump is running. This ensures even distribution and maximum effectiveness against algae growth. Always follow the manufacturer’s instructions for dosage and application to avoid overuse or underperformance.
Why shouldn’t I pour chlorine tablets directly into the pool water?
Chlorine tablets are formulated to dissolve slowly in water and are often designed to be used in a floating feeder or automatic chlorinator. Dropping them directly into the pool can cause them to sink to the bottom and dissolve unevenly, potentially bleaching the pool liner or damaging concrete surfaces. Additionally, localized high concentrations of chlorine can irritate the skin and eyes of swimmers.
To prevent these issues, always use a chlorine feeder or erosion feeder that allows for controlled release and proper dilution of the chlorine in the pool water. Also, never mix chlorine with other pool chemicals or substances, as this can cause dangerous chemical reactions.
Is it okay to pour pool water back into the pool after backwashing the filter?
While it may seem efficient to return water to the pool after backwashing, this practice can reintroduce contaminants into the pool system. Backwash water contains dirt, oils, algae, and other debris that were filtered out, and adding it back can immediately negate the cleaning process, causing the pool to become cloudy or unsafe faster than normal.
The best practice is to dispose of backwash water properly, following local regulations. After backwashing, reset the filter valve to ‘rinse’ for a few minutes before switching back to ‘filter’ mode. This helps ensure clean and clear water is returned to the pool, maintaining optimal water quality.
Can I put dish soap or laundry detergent into my pool to clean it?
Adding dish soap or laundry detergent into your pool is strongly discouraged. These soaps and detergents are designed to create suds and break down grease, but they can severely disrupt the chemical balance of the pool. They often contain enzymes, fragrances, and surfactants that can cloud the water, irritate skin and eyes, and cause foaming or scum buildup on pool surfaces.
Instead of alternatives not designed for pools, use phosphate removers, clarifiers, or pool-specific surfactants to clean and maintain the surface. Always ensure any product used in or around the pool is explicitly labeled for swimming pool use to avoid unintended consequences.
Is it safe to use old or expired chemicals to treat my pool?
Using old or expired pool chemicals is risky and often ineffective. Over time, chemicals like chlorine, algaecides, and pH adjusters can lose their potency, which means they won’t properly sanitize or balance the pool water. In some cases, expired chemicals may undergo chemical changes that cause them to react unpredictably or even dangerously when mixed with other substances.
It’s important to check expiration dates before using any pool chemicals and store them in a cool, dry, and well-ventilated area. If in doubt, replace expired products and follow proper disposal instructions for any outdated chemicals to maintain clean, safe, and properly balanced pool water.