Water Damage & Prevention
After a leak or flood: drying within 24–48 hours
In plain English
If wet materials are dried within 24 to 48 hours, mold generally won't take hold. Past that window, assume there is growth. The 48 hours is a rule of thumb, not a guarantee in either direction.
What to keep depends on the material. Hard, non-porous things can usually be cleaned and dried. Ceiling tiles and insulation that got wet should be thrown out. Drywall can sometimes be dried in place if it isn't swollen and the seams are intact. Carpet needs water extraction and fast drying, and so does the floor under it.
This applies to clean water. If the water came from sewage or a flood, it carries bacteria and other hazards, and the job needs professional protection and containment. Don't run fans until you know the water was clean — and don't run them once mold has started growing, because they spread it.
At a glance
| Material | What to do |
|---|---|
| Books and papers | Discard if not valuable. Copy valuable ones, or freeze / freeze-dry them. |
| Carpet and backing | Water-extraction vacuum, dehumidify, fans. Dry within 24–48 hours; clean and dry the subfloor too. |
| Ceiling tiles | Discard and replace. |
| Cellulose or fiberglass insulation | Discard and replace. |
| Concrete or block | Water-extraction vacuum; dehumidifiers, fans or heaters. |
| Vinyl, linoleum, ceramic tile | Vacuum or damp-wipe with mild detergent; check the underlayment is dry. |
| Plastics and metals | Vacuum or damp-wipe with mild detergent. |
| Upholstered furniture | Water-extraction vacuum and drying; hard to dry in 48 hours — call a restorer if valuable. |
| Drywall | Dry in place only if there is no swelling and seams are intact; otherwise remove and replace. |
| Drapes | Launder or clean per the maker's instructions. |
| Wood | Dry immediately; clean finished wood with mild detergent; pry wet paneling away to dry behind it. |
Key points
- Photograph everything and call your insurer before you start.
- Extract standing water, then dehumidify and ventilate.
- Discard what can't be cleaned and dried within 24–48 hours.
- No fans until the water is confirmed clean and no mold is growing.
Official text
CDC Mold Cleanup Guide — Introduction Best practice
Cleaning up after a flood can pose health risks. You and your family should wait to re-enter your home until professionals tell you it is safe, with no structural, electrical or other hazards.
Before you start cleanup activities, contact your insurance company and take pictures of the home and your belongings. Remember – drying your home and removing water-damaged items is your most important step for preventing mold damage.
Citation: CDC Mold Cleanup Guide, Introduction.
Read on the official site ↗ See it in the full CDC Mold Cleanup Guide
EPA 402-K-01-001 — Table 1: Water Damage – Cleanup and Mold Prevention pp. 10–11 Best practice
Table 1 presents strategies to respond to water damage within 24 – 48 hours. These guidelines are designed to help avoid the need for remediation of mold growth by taking quick action before growth starts. If mold growth is found on the materials listed in Table 1, refer to Table 2 for guidance on remediation. Depending on the size of the area involved and resources available, professional assistance may be needed to dry an area quickly and thoroughly.
Table 1: Water Damage – Cleanup and Mold Prevention
Guidelines for Response to Clean Water Damage within 24 – 48 Hours to Prevent Mold Growth*
| Water-Damaged Material† | Actions |
|---|---|
| Books and papers | • For non-valuable items, discard books and papers. • Photocopy valuable/important items, discard originals. • Freeze (in frost-free freezer or meat locker) or freeze-dry. |
| Carpet and backing – dry within 24 – 48 hours§ | • Remove water with water extraction vacuum. • Reduce ambient humidity levels with dehumidifier. • Accelerate drying process with fans. |
| Ceiling tiles | • Discard and replace. |
| Cellulose insulation | • Discard and replace. |
| Concrete or cinder block surfaces | • Remove water with water extraction vacuum. • Accelerate drying process with dehumidifiers, fans, and/or heaters. |
| Fiberglass insulation | • Discard and replace. |
| Hard surface, porous flooring§ (Linoleum, ceramic tile, vinyl) | • Vacuum or damp wipe with water and mild detergent and allow to dry; scrub if necessary. • Check to make sure underflooring is dry; dry underflooring if necessary. |
| Non-porous, hard surfaces (Plastics, metals) | • Vacuum or damp wipe with water and mild detergent and allow to dry; scrub if necessary. |
| Upholstered furniture | • Remove water with water extraction vacuum. • Accelerate drying process with dehumidifiers, fans, and/or heaters. • May be difficult to completely dry within 48 hours. If the piece is valuable, you may wish to consult a restoration/water damage professional who specializes in furniture. |
| Wallboard (Drywall and gypsum board) | • May be dried in place if there is no obvious swelling and the seams are intact. If not, remove, discard, and replace. • Ventilate the wall cavity, if possible. |
| Window drapes | • Follow laundering or cleaning instructions recommended by the manufacturer. |
| Wood surfaces | • Remove moisture immediately and use dehumidifiers, gentle heat, and fans for drying. (Use caution when applying heat to hardwood floors.) • Treated or finished wood surfaces may be cleaned with mild detergent and clean water and allowed to dry. • Wet paneling should be pried away from wall for drying. |
*If mold growth has occurred or materials have been wet for more than 48 hours, consult Table 2 guidelines. Even if materials are dried within 48 hours, mold growth may have occurred. Items may be tested by professionals if there is doubt. Note that mold growth will not always occur after 48 hours; this is only a guideline.
These guidelines are for damage caused by clean water. If you know or suspect that the water source is contaminated with sewage, or chemical or biological pollutants, then Personal Protective Equipment and containment are required by the Occupational Safety and Health Administration (OSHA). An experienced professional should be consulted if you and/or your remediators do not have expertise remediating in contaminated water situations. Do not use fans before determining that the water is clean or sanitary.
† If a particular item(s) has high monetary or sentimental value, you may wish to consult a restoration/water damage specialist.
§ The subfloor under the carpet or other flooring material must also be cleaned and dried. See the appropriate section of this table for recommended actions depending on the composition of the subfloor.
[6] Please note that Tables 1 and 2 contain general guidelines. Their purpose is to provide basic information for remediation managers to first assess the extent of the damage and then to determine whether the remediation should be managed by in-house personnel or outside professionals. The remediation manager can then use the guidelines to help design a remediation plan or to assess a plan submitted by outside professionals.
Citation: EPA 402-K-01-001, Table 1: Water Damage – Cleanup and Mold Prevention, pp. 10–11.
Read on the official site ↗ See it in the full EPA 402-K-01-001
CDC Mold Cleanup Guide — Is there a problem? Best practice
Was your home flooded? If so, and you were not able to dry your home (including furniture and other items) within 24-48 hours, you should assume you have mold growth. You need to completely dry everything, clean up the mold, and make sure you don't still have a moisture problem.
You may see or smell mold on clothing, drywall, furniture, cardboard boxes, or books, but it may also be hidden under or behind items like carpet, cushions, or walls.
Citation: CDC Mold Cleanup Guide, Is there a problem?.
Read on the official site ↗ See it in the full CDC Mold Cleanup Guide
CDC Mold Cleanup Guide — If I must do this myself, how can I do it safely? Best practice
Follow these steps:
- Put on the personal protective equipment described above to protect your eyes, nose, mouth, and skin.
- Remove standing water and wet materials. Use a wet vacuum to remove water from floors, carpets, and hard surfaces. Dry your home and everything in it as quickly as you can – within 24 to 48 hours if you can.
- Open all doors and windows when you are working and leave as many open as is safe when you leave.
- Open inside doors, especially closets and interior rooms, to let air flow to all areas. Take doors off their hinges if you need to.
- Open kitchen cabinets and bathroom vanity doors; remove drawers, wipe them clean, and stack them to dry.
- Open the attic access to let air flow to the attic. Before you open the attic door, make sure nothing will fall on you.
- When electricity is safe to use, use fans and dehumidifiers to remove moisture. Do not use fans if mold has already started to grow, because the fans may spread the mold.
- Clean with water and a detergent. Remove all mold you can see. Dry right away.
- If you use cleaning products, do not mix cleaning products together. DO NOT mix bleach and ammonia because it can create toxic vapors.
- Painting or caulking over mold will not prevent mold from growing. Fix the water problem completely and clean up all the mold before you paint or caulk.
- Throw away anything that was wet with flood water and can't be cleaned and dried completely within 24 to 48 hours. If you have precious items that you want to preserve, follow guidelines from the Smithsonian Institute: http://www.si.edu/mci/english/learn_more/taking_care/mnm.html
Citation: CDC Mold Cleanup Guide, If I must do this myself, how can I do it safely?.
Read on the official site ↗ See it in the full CDC Mold Cleanup Guide
Citations
- EPA 402-K-01-001, Mold Remediation in Schools and Commercial Buildings — Table 1, p. 11. Best practice Publisher's page ↗
- CDC Mold Cleanup Guide, Homeowner's and Renter's Guide to Mold Cleanup After Disasters — “Is there a problem?” and “If I must do this myself”. Best practice Publisher's page ↗