Can I make wudu with seawater or pool water?

Yes, you can make wudu with seawater, and with pool water as long as it is clean. The Prophet ﷺ said the sea's water is pure and purifying. Pool water with chlorine is still water, so it's valid too, unless it has visibly changed because of dirt or impurity.
Seawater is pure
Some sailors asked the Prophet ﷺ whether they could make wudu with seawater, since they carried only a little fresh water. He replied that its water is pure and purifying, and its dead animals are lawful to eat (Sunan Abi Dawud 83). Scholars of all four schools accept this. So on the beach, on a boat or on a cruise, you can make wudu straight from the sea. Salt water may leave your skin a bit sticky, but that doesn't affect your wudu. See Can I eat shrimp and other seafood?
Pool water and chlorine
Any water that is still called "water" (rain, rivers, lakes, the sea, tap water) can be used for wudu. Pool water is tap water with a small amount of chlorine and other chemicals. These don't change it into something else, so most scholars say wudu with it is valid.
The exception is water that has been changed by impurity, such as urine or faeces, so that its colour, taste or smell changes. Large amounts of water don't become impure from a small drop that leaves no trace, which is why a big public pool is generally fine. A small, cloudy paddling pool is another story. See Can I still go swimming at a public pool as a Muslim?
Does swimming count as wudu?
Getting wet all over doesn't count by itself. You need the intention, and most scholars say the order matters too (face, arms, head, feet). If you intend wudu and do the steps in order while in the water, it works. Otherwise, make wudu separately after your swim. See Does a shower count as wudu?
Other water you might wonder about
- Rain and snow melt: pure and fine for wudu.
- Lakes and rivers: fine, even if a bit murky from mud.
- Hot tub water: fine if it is clean and well kept.
- Flavoured or mixed drinks like tea or juice: not valid, since they're no longer plain water.
- The Prophet ﷺ called seawater pure and purifying.
- Chlorinated pool water is still water, so wudu is valid.
- Water changed in colour, taste or smell by impurity can't be used.
- Swimming only counts as wudu with intention and the right order.
People also ask
Do I have to make wudu for every prayer?
No, you don't need a new wudu for every prayer. One wudu lasts until it breaks, though renewing it for each prayer is a rewarded sunnah.
Read the full answer →How much water should I use for wudu?
Use just enough water for wudu to wet each part, ideally under a litre. The Prophet used about one mudd, and wasting water is disliked.
Read the full answer →Does swearing break wudu?
No, swearing does not break wudu in any of the four schools, but renewing it after angry words is recommended. Here is why it still matters.
Read the full answer →Does being naked break wudu?
No, being naked does not break wudu. Learn what does, why touching private parts is debated, and how to keep wudu after a shower.
Read the full answer →Does touching my private parts break wudu?
For most scholars, touching your private parts directly with the inner hand breaks wudu; Hanafis say it doesn't. Through clothes it never does.
Read the full answer →