Most houseplants can be watered with ordinary tap water if it is left to stand and used at room temperature, but rainwater or distilled water is safer for a few sensitive plants, and softened water should not be used. University of Nebraska NebGuide G2205: Houseplants says tap water can be used but should stand for at least 24 hours so chlorine and fluorine can dissipate, and that sensitive plants should be watered with rain water if possible. Illinois Extension: How to Water Houseplants says to avoid softened water and to use room temperature water, not cold. University of Missouri IPM: Leaf Tipburn on Houseplants goes further and says never to water houseplants with water that has passed through a water softener.
The sources agree on most points and stay silent on others, especially on rainwater storage and on which fragrant plants are sensitive. This page sets out what was read, where the pages overlap, and what they leave out. For how often to water, see Overwatering or Underwatering: Which Drops Flower Buds?.
What each source says about water type
| Water | Illinois | Nebraska | Missouri | WSU | RHS |
|---|---|---|---|---|---|
| Tap, left to stand | Stand 24 hours for chlorine and fluoride | Stand at least 24 hours for chlorine and fluorine | Not mentioned as a fix | Let chlorinated water stand overnight | Stand for a minimum of 24 hours so chlorine dissipates |
| Softened | Avoid; can damage some plants | Not mentioned | Never use | Do not use unless deionised | Not mentioned |
| Rainwater | Not mentioned | Best for sensitive plants where possible | Rainwater or distilled for fluoride-sensitive plants | Not mentioned | Best for ericaceous (acid-loving) plants |
| Distilled | Not mentioned | Not mentioned | Named for sensitive plants | Not mentioned | Not mentioned |
| Temperature | Room temperature, not cold | Always room temperature | Not mentioned | Room temperature | Room temperature, especially in winter |
Note the detail in the Missouri row: it names rainwater or distilled water for sensitive plants, but it does not recommend standing as a remedy for fluoride. The Illinois and Nebraska pages say standing water lets chlorine and fluoride, or fluorine, dissipate, but none of the opened pages explains the mechanism. If a plant shows tip scorch, do not assume a day of standing has solved the problem.
Fluoride: the real reason to change water
University of Missouri IPM: Leaf Tipburn on Houseplants says many public water sources contain trace amounts of fluorides and that, given enough time, sensitive plants can accumulate enough from this water to show toxicity symptoms. It says members of the lily family are especially sensitive. It also says perlite contains fluorides, and for sensitive plants it suggests a medium free from perlite and watering only with rainwater or distilled water. The Nebraska guide names Dracaena, Cordyline and Chlorophytum as plants that should get rainwater where possible, and WSU names peace lily as sensitive to fluoride.
None of those pages names jasmine, gardenia, hoya, citrus or stephanotis as fluoride-sensitive. So the sources give no basis for treating a fragrant plant differently from other houseplants on fluoride grounds. If a fragrant plant develops brown tips, the Missouri page lists three common causes: excessive fertiliser, improper watering and fluoride toxicity, in that order, so check the first two before changing your water.
Softened water
This is the clearest instruction in the sources. Missouri says never to use it and adds that it tends to add to the problem of excess salts in the root zone. WSU says not to use softened water unless it has deionising treatment. Illinois says to avoid it because it can damage some plants. The Missouri page does not explain how softeners add salts, so the reason is not given beyond that.
Rainwater and acid-loving plants
The RHS: How to grow houseplants says ericaceous plants do best with rainwater because hard tap water is alkaline, which is the reason it gives for plants that need acidic conditions. Whether a given scented plant counts as acid-loving is a plant-specific question: the RHS gardenia page is where that is described for gardenia, and Watering Gardenia: Tap Water, Rainwater and Mineral Build-Up follows up. The general pages above do not list any scented houseplant as acid-loving.
Mineral build-up: how to spot it
Missouri says dry potting mix loses water but not fertiliser salts, so the solution becomes more concentrated, and a whitish residue on the surface means the medium should be flushed with clear water. It also advises emptying drainage water to prevent wicking fertiliser back into the pot. WSU recommends flushing every four to six months using water equal to twice the pot volume.
A practical routine from the sources
- Use room temperature water (Illinois, Nebraska, WSU, RHS all say so).
- If you use tap water, fill the can and leave it for 24 hours (Illinois, Nebraska, RHS).
- Avoid softened water entirely (Missouri, WSU, Illinois).
- For fluoride-sensitive plants, use rainwater or distilled water (Missouri, Nebraska).
- Water until it drains from the bottom, and empty the saucer (WSU, Illinois, RHS).
- Flush every four to six months (WSU) and when a white crust appears (Missouri).
What the sources do not cover
None of the opened pages says how to collect or store rainwater safely, how long rainwater keeps, whether well water is suitable, or what filtered or bottled water does for plants. The University of Maryland and UC pages that discuss softened and well water could not be opened for this page, so their claims are not used. No source tests water type against flowering in scented houseplants.
Frequently asked questions
Is tap water safe for houseplants?
The sources say it can be used. Nebraska says it should stand for at least 24 hours, and Illinois and the RHS agree.
Does standing water remove fluoride?
Illinois and Nebraska say it lets chlorine and fluoride, or fluorine, dissipate. Missouri recommends rainwater or distilled water for sensitive plants and does not suggest standing as a fix.
Can I use water from a water softener?
No. Missouri says never, and WSU says only if it has deionising treatment.
Should water be cold or warm?
Room temperature, according to every source that mentions temperature. Illinois says not cold.
Sources read for this page
- University of Nebraska NebGuide G2205: Houseplants
- Illinois Extension: How to Water Houseplants
- University of Missouri IPM: Leaf Tipburn on Houseplants
- WSU Extension: Houseplants (PNW Gardeners Handbook)
- RHS: How to grow houseplants
Last reviewed 25 October 2026. Written by Md. Firozur Rahman. This page gives general guidance and cannot diagnose a plant from a description; see the Disclaimer. Browse more in Getting Blooms Indoors.
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