Another corruption scandal implicating prominent officials has been uncovered by the Egyptian government, the latest in a series of cases that have jolted a country where corruption is so ingrained it is part of the folklore.

In the latest case here, reported on the front pages of today's newspapers, the public prosecutor announced the indictment of Ezzedin Farag, chairman of the board of directors of the Cairo Water Authority and a member of parliament.

He is accused of "gross negligence" that cost the government nearly $4 million, according to charges read at a press conference by Prosecutor General Anwar Abu Sehly. The prosecutor said Farag's property has been impounded and said the prosecution would ask to have Farag's parliamentary immunity lifted so he can be tried.

Since Mustapha Khalil became prime minister in October and proclaimed that corruption would not be tolerated, the government has moved swiftly on several politically sensitive cases. All have received extensive press coverage.

They represent only the tip of the iceberg, Egyptians agree, but they may presage a wider campaign. Public Prosecutor Anwar Abu Sekhla, announcing the indictment of two former Cabinet ministers in a case involving alleged payoffs by the Boeing Aircraft Corp., said it would show that Egypt is "under the rule of law" and that "there is no difference between the great and the small, the weak and the powerful."

Sophisticated Egyptians, whose cynicism about the country's corruption is mixed with curiosity about the meaning of the latest campaign and about how far it will go, say it has clear political implications.

President Anwar Sadat and members of his entourage have been criticized by dissident groups of the left and right for their lavish lifestyles, and grumbling among ordinary Egyptians forced to pay bribes for every service is said to be on the increase. Sadat has acknowledged his deep concern about the events in Iran, where high-level corruption is among the grievances that have threatened Sadat's friend and ally, the shah.

At the news conference at which Farag's indictment was announced, the prosecutor also said his office is investigating charges that officials of a state-owned textile company stole more than $800,000.

That was a reminder that a parallel inquiry is under way in parliament to find out who authorized, and who benefited from, the decision by a state-owned bank to lay out millions of dollars in scarce foreign currency to build a new private textile plant that is not part of the government's development plan and would compete with the state-owned factories. That project was suspended by Khalil's predecessor, Mamdouh Salem.

Last month, two former Cabinet ministers, a former consultant to the national airline and two former airline officials were indicted on charges of taking bribes and neglecting their duty in the purchase of four Boeing 707 jetliners in 1972.

One of those named was former deputy prime minister Abdullah Merziban. It is said to be the first time here that an official of such high rank was indicted on criminal corruption charges.

The prosecutor general has also moved to revoke the parliamentary immunity of another former deputy prime minister, Ahmed Sultan Ismail, in anticipation of filing charges against him. Sultan, who was also minister of power until Sadat reshuffled the government in October, has been named in a Washington court case as the recipient of a $322,000 bribe from the Westinghouse Corp. in connenction with a power plant contract.

That case did not originate here. The government's hand was forced by the developments in the Washington case, where Westinghouse has admitted paying the bribe. But Egyptians were impressed by the swiftness with which the government responded to the Washington charges, giving them a full airing in the press and publicizing an agreement with the United States to exchange information about the case.

Sultan has proclaimed his innocence and a lawyer who represented Westinghouse here gave an interview to a Cairo newspaper that suggested other prominent persons may also have received money. A long investigation is in prospect.

Egyptians say that the cleaning up of corruption here is a more difficult and complex problem that it would be in the United States, first because the definitions are less clear cut and second because the giving of gifts and commissions is a widespread practice in the Middle East that is condoned by tradition.

It is common for government officials to run private businesses on the side, for example, or for officials of state-owned industries to channel contracts to relatives and business associates.