# Dehumidifiers A dehumidifier only works when it is sized for the space and the water it collects can leave the room. These guides cover sizing, placement, drainage and maintenance so the unit actually dries the space instead of cycling on and off. _Last updated: 2026-09-28_ ## What you will find here - Sizing a dehumidifier for a basement, bedroom or crawl space - Continuous drainage setup and common mistakes - Why a unit stops collecting water - Tank cleaning and long-term running cost ## Frequently asked questions **Q: What size dehumidifier do I need?** A: Start from the space and the dampness: a moderately damp basement up to about 1,500 ft² is often served by a 30-pint class unit, while very damp or larger spaces need more capacity. Match the pint rating to your conditions rather than the room size alone. **Q: Can I run a dehumidifier overnight?** A: Yes, if the unit is in good condition and the room is ventilated to the extent the instructions require. Continuous drainage avoids a full tank stopping the unit overnight. ## Products in this category - [DREO 4500 Sq Ft Smart Dehumidifier](https://www.amazon.com/dp/B0HFJ84RXX?maas=maas_adg_api_585602613512925350_static_12_201&ref_=aa_maas&tag=maas&aa_campaignid=PBd80bd4ce4ece40f44bcc76fcc0c48425&aa_adgroupid=d727cvIagGJNdGXDUz0Iqptw7I5s_aKKkTwS73Xa_a_b7ETmu9M7Nt_a8HDUDltLqXHEoBPCPgPBICz6Ie8_aV7Dy&aa_creativeid=3a3f9E4uc79Tu869imL_bB9Ebro5FEwJkM_aTxcggToEdOXnw_c) — Best for: Large, damp basements. Amazon rating 4.3/5 (244 reviews). ASIN B0HFJ84RXX. - [DREO Energy Star Smart Dehumidifier](https://www.amazon.com/dp/B0GXY4C7NL?maas=maas_adg_api_585602613512925350_static_12_201&ref_=aa_maas&tag=maas&aa_campaignid=PBd80bd4ce4ece40f44bcc76fcc0c48425&aa_adgroupid=4df6yIkxpU3HN0REPqSNVtr6seTnE_aWp4t3Cqix8FL7SFdlrNERs9WYf2RDnowHAbQ7k5GcZAmD0uiaC3wUr&aa_creativeid=28f2gCwkqMXEzilBT4juHu3jBs9kdOytbk8aQjUCLZU4oS0_c) — Best for: Moderately damp basements and rooms. Amazon rating 4.3/5 (244 reviews). ASIN B0GXY4C7NL. _Specifications and ratings are manufacturer/retailer figures, not SmartAirGuide measurements. Some links are affiliate links._ --- Canonical: