Over the weekend, parts of Japan received between 300 to 500 millimeters (12 to 20 inches) of rain, with prefectures of Hiroshima, Okayama, and Hyogo inundated with more than 500 millimeters.
In addition to the water outage, people in afflicted areas were plagued with severely hot weather.
The government is also focusing on restoring the roads and the water supply. Phone lines and electricity generators also took a beating, as did water sources and other basic necessities.
The landslides and flooding across much of western Japan have killed at least 155 people, Chief Cabinet Secretary Yoshihide Suga told a news conference.
"We have to prioritize (which train services) can resume, according to their importance", a JR West official said.
A local resident walks in a flooded area in Mabi town in Kurashiki, Okayama Prefecture, Japan, July 9, 2018.
"The area became an ocean", 82-year-old resident Nobue Kakumoto told AFP Sunday, surveying the scene.
Areas impacted by the flooding in Japan.
Construction worker Fukuyoshi Doi volunteering to get that done, and supervised other volunteers who gathered to help. Convenience stores are open shorter hours, and dozens of outlets of major chains such as Family Mart, 7-Eleven and Lawson were closed due to delayed deliveries, supply shortages or flooding in Hiroshima, Okayama and Ehime.
Hundreds of thousands of people were forced to flee their homes, and those unable to leave took shelter on rooftops as the streets filled with water. At a major supermarket in town, employees sold bottled water and tea, cups of noodles and other preserved foods that survived the floods, while employees cleaned damaged merchandise, throwing items into dozens of plastic bags. Residents lined up for water under a scorching sun as temperatures rose to 35 Celsius (95 Fahrenheit), raising the risk of heat stroke.
At one point during the flooding, evacuation orders were given for almost 6 million people across 19 prefectures. Many returned to on their homes and begin cleanup Monday after the rain stopped and weather warnings were lifted.
Both emergency services, households and evacuees have struggled with telecommunications services as NTT West said that almost 16,000 landlines and internet connections are down affecting an expansive area of western Japan.
Officials have evacuated about two million people after rives banks burst.
On Thursday, he pledged to ramp up help for affected areas and said the government had secured around 71,000 temporary homes for evacuees.
He said the government had been making "every effort to deal with this crisis since the disaster occurred".
Japan's government says Prime Minister Shinzo Abe has cancelled his planned July 11-18 trip to Europe and the Middle East to oversee the emergency response to deadly heavy rains.
According to the Japan Meteorological Agency (JMA), an active seasonal rain front caused torrential rain in most eastern and western regions of Japan since last Thursday.