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Water Damage – Understanding the Different Categories of Contaminated Water

Hurricane Harvey Houston flooding

Dangerous and devastating, water damage is one of the most common types of damage that affects a home. It can be caused by anything from sewage backups to torrential rains and, if not dealt with correctly, it poses significant risks not only to the property, but to your health as well.

It is, therefore, essential to know how to respond to flooding in a timely and efficient manner in order to limit the extent of the damage and prevent further problems. And since water damage can come from so many sources, it’s crucial to understand the risks associated with different types of contaminated water and to know the specific procedures required to mitigate different types of damage.

The professional guide below will provide you with all the information you need about the effects of contaminated water, the categories of water damage, and the steps you can take to keep your home and family protected in the aftermath of a flood.

Types of Contaminated Water and Categories of Water Damage

Flood Damage Restoration in Bay Area, TXOne of the first things to do when faced with water damage is determine what kind of contamination you’re dealing with. According to the Natural Resources Defense Council (NRDC), water can be contaminated by agricultural pollution, oil pollution, sewage and wastewater, radioactive substances, harmful chemicals, and various other materials.

Different types of contaminated water pose different risks, but the longer the water stays in a home, the more severe the property damage it will cause and the greater the threat to your health.

The affected area must be cleaned and disinfected as soon as possible – the appropriate clean-up procedures and required safety protocols, however, will vary depending on the type of water damage (mitigating water damage from a burst pipe will be very different from restoring water damage from a hurricane, of course).

The Institute of Inspection Cleaning and Restoration Certification (IICRC) defines three types of water damage based on the source of the flood water, the presence of harmful chemicals or other contaminants in it, and the amount of time it has stayed in the home. Each category of water damage must be dealt with according to its specific safety and restoration requirements.

Category 1 Water Damage

Category 1 water is clean water from broken pipes, leaky faucets, melting snow, rain, etc. Although it poses no immediate health concerns, category 1 water doesn’t come without risks.

What are the risks of category 1 water?

Category 1 water comes from clean and sanitary sources, so it is generally harmless to humans and pets. If not removed quickly, however, it can cause significant damage to the home and lead to health issues – clean water can degrade into category 2 water within 24 hours and cause toxic mold growth in as little as 48 hours. Once mold starts developing in the home, it will spread quickly and not only cause damage to the building structure, household items, and personal belongings in the home, but also pose severe health risks to the inhabitants.

How to clean category 1 water?

Category 1 water is relatively easy to clean up and doesn’t require specialized equipment or expert skills. Restoring Category 1 water damage involves fixing the source of the excess moisture (if relevant), removing the standing water, and drying the affected area.

Category 2 Water Damage

Also referred to as grey water or sullage, Category 2 water contains contaminants that could be harmful to people and animals. The most common sources of Category 2 water damage include overflowing toilets, malfunctioning appliances such as dishwashers and washing machines, and sump pump failures.

Grey water can cause severe property damage and pose significant threats to human health.

What are the risks of category 2 water?

Water Damage Restoration and Flood Cleanup in Splendora, TXGrey water may contain small amounts of detergents or other harmful chemicals (from discharge from washing machines or dishwashers), urine or other bio-contaminants (from toilet overflows or sump pump back-ups) and other forms of contamination that are hazardous to human health. Substances like soap particles, grease, food residue, and cleaning chemicals that are commonly found in Category 2 water could cause sickness or discomfort if they’re ingested or come in direct contact with broken skin. The disease-causing organisms can be easily transferred through contaminated hands as well.

The most common health issues associated with Category 2 water damage include different allergic symptoms, asthma, rhinitis, burning eyes, skin irritation, inflammatory problems, nausea, headache, and fever.

If left untreated, Category 2 water can turn into Category 3 water within 48 hours due to bacteria growth. Mold will also start developing in the home and will cause greater property damage and more severe health issues.

How to clean category 2 water?

Dealing with Category 2 water damage involves:

  • Fixing the problem that caused the water spill;
  • Removing the excess water;
  • Cleaning and disinfecting hard surfaces, drywall, carpeting, rugs, upholstered furniture, and other affected household materials and items;
  • Thoroughly drying the structure and all household contents;
  • Cleaning or disinfecting the HVAC equipment to prevent it from recirculating mold spores in the home environment.

Since Category 2 water is dangerous to the health and can cause extensive damage to the home, the cleaning process should be left to the professionals. The experienced water damage restoration technicians have the knowledge, skill, and specialized equipment to fix the problem quickly and efficiently and prevent further trouble.

Category 3 Water Damage

Hurricane Harvey TX floodAlso called black water, Category 3 water is water from sewage backups and overflowing rivers that contains various hazardous contaminants, sewage, and/or toxic debris. According to the Institute of Inspection Cleaning and Restoration Certification (IIRC) and the Environmental Protection Agency (EPA), all water originating from sea water, ground or surface water, rising rivers and streams, and wind-driven rain from hurricanes and tropical storms is considered to be Category 3.

Black water is highly contaminated, contains bacteria, pathogens, and harmful chemicals, and can cause serious illness or even death in extreme conditions.

Category 3 water contamination is not only extremely dangerous, but also highly destructive.

What are the risks of category 3 water?

Sewage water and flood water bring in various chemicals and toxic debris, as well as silt and other organic matter that may already have bacteria growing in it. These contaminants can cause serious health problems such as bacterial infections from E. coli, salmonella, and shigella, virus infections like rotavirus, hepatitis, and echovirus, and even parasitic diseases such as giardia infection, cryptosporidium infection, and others.

Due to the unsanitary conditions of the water, any affected porous materials like drywall, upholstery, and carpets are completely unsalvageable and must be replaced during the restoration process.

How to clean category 3 water?

Black water cleanup is risky and difficult – it should be handled by experienced professionals who have the advanced equipment and technical know-how to safely remove the water, disinfect the area, and repair the damage. The water damage mitigation process includes:

  • Extracting the excess water;
  • Removing porous materials – wood items, carpets, drapes, insulation, and any other permeable building materials and porous household items that may have absorbed dangerous contaminants must be removed and discarded in order to eliminate the risk of contamination and reduce the likelihood of toxic mold growth;
  • Cleaning and disinfecting salvageable items and materials;
  • Drying the building structure and household contents;
  • Cleaning and disinfecting the HVAC system;
  • Repairing damaged structural components;
  • Restoring the healthy living environment and excellent condition of the home.

Water Damage Mitigation by ServiceMaster Restoration & Cleaning

Water Damage CleanupIn the unfortunate event of water damage, bacterial growth can begin within hours. To prevent severe damage to your property and serious threats to your health, you need to take quick and efficient measures immediately after the disaster – calling an experienced and trustworthy water damage restoration company, such as ServiceMaster Restoration and Cleaning, is your best bet for a complete recovery. Our knowledgeable, skilled technicians can dramatically reduce the extent of the damage through immediate emergency water extraction and implementation of effective drying and dehumidification techniques. We offer:

  • 24/7/365 emergency extraction and dehumidification services;
  • Water cleanup and debris removal;
  • Sanitization and anti-microbial application;
  • Consistent moisture monitoring throughout the entire drying phase;
  • Air quality control;
  • Water damage repair;
  • Mold remediation;
  • Carpet and upholstery cleaning;
  • Temporary storage and inventory for water damaged contents;
  • Coordination with insurance companies.


With our quality water damage restoration services, ServiceMaster Restoration and Cleaning will help you get your life back on track quickly and efficiently. You can find us at (800) 303-5844 any time of the day and night for water mitigation, water removal, basement flooding clean up, and any other water damage restoration services you may need in the Houston, TX area.