Cleaning, disinfection, and common myths

01 — Never mix bleach with ammonia

The combination produces chloramine gas, which causes respiratory damage and can be fatal in confined spaces.

The danger is that ammonia hides in many common products: glass cleaners, multi-surface sprays, some oven cleaners, some floor cleaners, and even urine (relevant when cleaning toilets, litter boxes, or diaper pails with bleach). During a disruption, when people are improvising cleaning solutions from whatever is available, the risk of accidental mixing increases.

• Never mix bleach with any other cleaning product. The only safe thing to add to bleach is water.
• If you accidentally mix bleach with ammonia or any other chemical and notice fumes, leave the area immediately. Get to fresh air. Call Poison Control (1-800-222-1222) or 911 if you have difficulty breathing.
• Bleach mixed with acid (vinegar, some bathroom cleaners, citrus-based cleaners) produces chlorine gas, which is also toxic. The rule applies to acids as well as ammonia.
• When using bleach for disinfection, ensure ventilation: open a window or door, or work outdoors.

02 — Disinfecting water storage containers

Wash with soap, rinse, then sanitize with a dilute bleach solution before filling with drinking water.

Any container used for storing drinking water must be sanitized before use, whether it is new or reused. Even food-grade containers can harbor bacteria from manufacturing, shipping, or prior contents. The procedure is straightforward:

• Wash the container thoroughly with dish soap and clean water. Scrub the interior with a bottle brush if possible, paying attention to the threads and cap area.
• Rinse all soap residue with clean water.
• Prepare a sanitizing solution: 1 teaspoon of unscented household liquid bleach (5-8% sodium hypochlorite) per quart of water.
• Pour the sanitizing solution into the container. Close the cap and shake or swish so the solution contacts every interior surface, including the cap and threads. Let it sit for at least 30 seconds.
• Rinse with clean water and allow to air dry.
• Fill with clean drinking water and seal. Store in a cool, dark place.

03 — Norovirus cleanup

Gloves, mask, blot (do not wipe or spray), sealed disposal, and a bleach solution five to ten times stronger than normal cleaning strength.

Norovirus is one of the most contagious pathogens a household can encounter. It spreads through direct contact with an infected person, through contaminated surfaces, and through aerosolized droplets from vomit. A single episode of vomiting can release billions of virus particles into the environment, and it takes fewer than 20 particles to infect another person. Cleanup must be treated as a biohazard procedure, not routine cleaning.

• Protect yourself: Put on disposable gloves and a mask before approaching the contaminated area. Norovirus can become airborne when disturbed.
• Blot, do not wipe or spray: Use paper towels to blot up visible vomit or diarrhea. Wiping spreads contamination across a wider area. Spraying cleaning solution onto contaminated material can aerosolize virus particles.
• Dispose of contaminated materials: Place all paper towels, gloves, and any contaminated disposable items into a plastic bag. Seal the bag before placing it in the trash.
• Disinfect with a strong bleach solution: The CDC recommends 5 to 25 tablespoons of household bleach (5-8% sodium hypochlorite) per gallon of water for norovirus. This is 5 to 25 times stronger than the standard cleaning concentration. Apply the solution to the entire contaminated area and a surrounding margin. Leave it wet for at least 5 minutes. Allow to air dry.
• Wash laundry on hot: Any clothing or linens contaminated with vomit or diarrhea should be washed with detergent on the hottest available cycle and machine dried on the highest heat setting.
• Wash hands with soap and water: Hand sanitizer does not work well against norovirus. Soap and water, scrubbing for at least 20 seconds, is required.

04 — Post-flood disinfection

Remove porous materials that absorbed flood water. Clean hard surfaces with soap. Then disinfect with bleach. That order matters.

Flood water is not clean water. It may contain sewage, agricultural runoff, chemical contaminants, petroleum products, and pathogens. Everything the water touched must be evaluated and either cleaned, disinfected, or discarded.

• Discard porous materials: Carpet, carpet padding, drywall below the flood line, insulation, upholstered furniture, mattresses, and any fabric or paper product that absorbed flood water cannot be reliably disinfected and must be removed and discarded. The interior of these materials will harbor bacteria and mold regardless of surface treatment.
• Clean hard surfaces first: Wash all salvageable hard surfaces (concrete, tile, metal, hard plastic, wood framing) with soap and water to remove visible dirt, mud, and debris. Disinfectant applied to a dirty surface is less effective because organic matter neutralizes the active ingredient.
• Disinfect: After cleaning, apply a bleach solution (1/3 cup household bleach per gallon of water, or approximately 5 tablespoons per gallon) to all cleaned hard surfaces. Allow to air dry. Open windows and doors for ventilation.
• Dry everything: The most important step after cleaning is thorough drying. Mold begins growing on wet surfaces within 24 to 48 hours. Use fans, dehumidifiers, and open windows to dry the structure as quickly as possible. Any surface that remains wet will grow mold regardless of how well it was disinfected.

05 — Improvised cleaning supplies

When commercial products run out, dish soap, baking soda, and white vinegar handle most household cleaning tasks.

During an extended disruption, commercial laundry detergent, surface cleaners, and specialized products may not be available. The following substitutes are effective for most cleaning needs:

• Dish soap for laundry: A small amount of liquid dish soap (2 to 3 teaspoons per small load) works for hand-washing clothing. Use sparingly, as dish soap produces more suds than laundry detergent and requires more rinsing water.
• Baking soda: A mild abrasive cleaner for surfaces, pots, and pans. Also deodorizes fabrics and surfaces. Mix with a small amount of water to form a paste for scrubbing.
• White vinegar: Effective against many bacteria and some mold species on hard surfaces. Works as a rinse agent for laundry (1/2 cup in the rinse cycle removes soap residue and softens fabric). Do not mix with bleach.
• Bleach: The most effective household disinfectant when used correctly. The CDC standard disinfection concentration is 5 tablespoons (1/3 cup) per gallon of water for general surface disinfection. Use unscented household bleach only (5-8% sodium hypochlorite). Make solutions fresh daily, as bleach loses potency over time once diluted.

Myth 01

Hand sanitizer with at least 60% alcohol is effective against many pathogens, but it has real limitations that soap and water do not.

The CDC recommends alcohol-based hand sanitizer (60% or higher alcohol content) as an acceptable alternative to handwashing in many situations, but explicitly states it is not a replacement. The limitations:

• Hand sanitizer does not work well on visibly dirty or greasy hands. The organic matter prevents the alcohol from contacting the pathogens on the skin surface.
• Hand sanitizer does not effectively kill norovirus, the most common cause of gastroenteritis outbreaks. The CDC states that hand sanitizer should not be used as a substitute for handwashing during a norovirus outbreak.
• Hand sanitizer does not remove chemical contaminants, pesticides, or heavy metals from hands.
• Hand sanitizer does not kill Clostridioides difficile (C. diff) spores or Cryptosporidium.

After using the toilet, after handling raw meat, after changing a diaper, and during any gastrointestinal illness outbreak, soap and water is required. Hand sanitizer is appropriate for situations where hands are not visibly soiled and soap and water are genuinely unavailable.

Myth 02

Bleach kills mold on non-porous surfaces like tile and glass. On porous surfaces like drywall and wood, it makes the problem worse.

This is one of the most persistent and damaging cleaning myths. The EPA and OSHA both explicitly state that bleach is not recommended as a routine practice for mold remediation. The chemistry explains why.

Household bleach is approximately 90 to 95% water. When applied to a porous surface like drywall, wood, or grout, the chlorine component stays on the surface and kills visible mold. But the water component soaks into the material, reaching the mold's root structures (hyphae) that extend below the surface. The roots receive moisture, the surface appears clean, and the mold regrows, often within days, frequently more aggressively than before.

On non-porous surfaces (tile, glass, sealed countertops, porcelain), bleach works as expected: the chlorine contacts and kills the mold, and the water cannot penetrate the surface to feed roots. For these surfaces, bleach is effective.

The correct approach for mold on porous surfaces: remove and replace the affected material. Moldy drywall, insulation, and carpet padding should be cut out, bagged, and discarded. The underlying cause of the moisture must be identified and fixed. Without addressing the moisture source, no cleaning method, including professional remediation, will prevent the mold from returning.