According to Ukraine, the size of the Kherson region's flood plain has almost halved since the Kakhovka dam breach, but experts and officials are concerned that infectious diseases could spread in the area's polluted waters.
According to Alexander Prokudin, the head of the regional administration, the water levels have fallen by 27 cm (10 in).
Thousands of homes and dozens of settlements in Ukraine are still under water, according to the interior ministry.
There are thousands without access to water.
Large tracts of land on both sides of the Dnipro river were quickly inundated by water after the major dam burst on Tuesday, releasing a tremendous torrent of water.
The dam was "blown up," according to Ukraine, and it was situated in a region of Ukraine that was under Russian control. This was refuted by Russia, which also charged Ukraine with causing its demise.
Although neither claim has been confirmed by the BBC, it appears likely that Russian forces, who were in control of the dam, decided to detonate it in order to make things more difficult for Ukraine's ongoing counteroffensive.
The enormous Kakhovka reservoir, which had provided the area with essential water supplies, had dried up behind the dam.
According to Dr. Jarno Habicht, WHO's representative for Ukraine, the situation is "devastating," and getting people access to safe, clean water is a top priority. He stated that ongoing precautionary sample testing was being done and that it was crucial to keep an eye on water-borne illnesses.
According to the UK defense ministry, there is a "sanitation crisis," with people having little access to clean water and a higher chance of contracting water-borne illnesses.
The city of Kherson, which is about 100 kilometers (62 miles) from the Kakhovka dam and was severely affected by the floods, has put restrictions on the use of river water in an effort to stop the spread of infectious diseases, despite the claim of Ukrainian officials that no cases have been reported thus far.
According to the city military administration, the water is now highly polluted as a result of the flooding of homes and sewage facilities, making it illegal to bathe in, fish in, drink from, or give water to animals.
According to the interior ministry of Ukraine, 32 settlements in the portion of Kherson that is under Ukrainian control and 14 more in the portion under Russian control were flooded. In the Mykolayiv region, 31 additional settlements were flooded. .
Water supplies to Crimea, which Russia illegitimately annexed in 2014, have likely been disrupted as a result of the destruction of the Kakhovka dam.
The Kakhovka reservoir, which is behind the now-destroyed dam, serves as the North Crimean Canal's water source.
The water level in the reservoir has dropped by more than 7 meters (23 feet), according to the Ukrainian hydro energy company Ukrhydroenergo, and the UK defense ministry issued a warning on Sunday that "water will soon stop flowing" to the peninsula.
Drone video captured after the dam breach appears to show significantly lower water levels close to the canal entrance.
Whoever was in charge of destroying the Kakhovka dam did so with the knowledge that Crimea would be without the fresh water it so desperately needed.
After Ukraine annexed Crimea in 2014, Russia quickly unblocked the canal after invading southern Ukraine the following year.
It's possible that Russian commanders came to the extreme but necessary conclusion that delaying Ukraine's military preparations was worth blowing up the dam in order to render the waterway useless once more.
The long-awaited Ukrainian counteroffensive against Russia officially began earlier, according to Ukrainian President Volodymr Zelensky.
He declared on Saturday that both defensive and counteroffensive actions were in progress.
According to reports, Ukrainian forces have pushed forward in the east near Bakhmut and in the south near Zaporizhzhia and have launched long-range attacks on Russian targets.
It can be challenging to evaluate how things really are on the ground. According to the reputable US-based think tank Institute for the Study of War, although Ukrainian forces appear to have made some small-scale gains, they have had difficulty getting past Russian positions that are deeply entrenched.
Meanwhile, a freight train derailed on Saturday night in the Belgorod region of Russia, which borders Ukraine.
Drones, shelling, and cross-border raids have recently targeted Belgorod's border regions.
Vladislav Shapsha, the governor of the Kaluga region, claimed there had been two drone crashes, one close to the village of Strelkovk and the other in a forest, further north.
The incidents have not been verified independently by the BBC.
Paul Adams contributed more information.
