zhídào shuǐguǎn wéixiū hǎo le, gōngshuǐ cái huīfù.

This is a very common pattern meaning not until ... did ...

In this sentence:

• 直到水管维修好了 = until the water pipes had been repaired
• 供水才恢复 = the water supply only then resumed

So the full structure emphasizes that the second event did not happen before the first one was completed.

A very natural English equivalent is:

• Not until the pipes were repaired did the water supply resume.

才 often means only then, not until then, or only after that.

Here it shows that 恢复 happened later, and only after the condition in the first clause was met.

Compare:

• 直到水管维修好了，供水恢复。
  This sounds more like a plain statement: the water supply resumed after the pipes were repaired.

• 直到水管维修好了，供水才恢复。
  This clearly emphasizes: the water supply didn't resume before that point.

So 才 is important for the sense of delay or dependence.

It can be broken down like this:

• 维修 = to repair; to carry out maintenance
• 好 = a result complement meaning successfully, properly, or to a completed/good state
• 了 = marks completion or a new state

So 维修好了 means:

• have been repaired successfully
• have been fixed
• are repaired now

The 好 here does not mean good in the usual adjective sense. It shows the result of the action.

Because in Mandarin, result complements come after the verb.

So:

• 维修 = repair
• 维修好 = repair something so that it is fixed
• 维修好了 = repaired and now in a fixed/completed state

This is a very common pattern in Chinese:

• 写好 = write and finish it well
• 做好 = do/make and complete it properly
• 修好 = repair and fix successfully

So 维修好 follows a normal Chinese verb + result complement structure.

Because Chinese often leaves out the agent when it is unknown, obvious, or unimportant.

Here, the focus is on the state of the pipes, not on who repaired them. So 水管维修好了 naturally means something like:

• the pipes were repaired
• the pipes had been fixed

Using 被 is possible in some contexts, but it would sound heavier and more explicitly passive. In this sentence, that is unnecessary.

So this is a very natural, concise Chinese way to express the idea.

Here 供水 is functioning like a noun-like subject, meaning:

• water supply
• water service

Then 恢复 is the main verb:

• 供水恢复 = the water supply resumed / was restored

Even though 供水 can also be verbal in other contexts, in this sentence it is best understood as the supply of water.

Good question. Chinese does not always need 了 on every completed action.

Here, the sentence already has strong timing/completion signals:

• 直到... sets the endpoint
• 才 shows the delayed occurrence
• 维修好了 already contains 了

Because of that, 恢复 can appear without 了 and still sound complete and natural.

You may also see 供水才恢复了 in some contexts, but the version without 了 is very standard here and often sounds a bit cleaner.

Chinese often puts time, condition, or background information first.

So the sentence is organized like this:

1. 直到水管维修好了 = first set the time/condition
2. 供水才恢复 = then state the main event

This is very natural in Mandarin. It helps the listener understand the condition before hearing the result.

It is similar to English sentences like:

• After the pipes were repaired, the water supply resumed.
• Not until the pipes were repaired did the water supply resume.

Yes, in many contexts 等到 can work:

• 等到水管维修好了，供水才恢复。

This is also natural.

The difference is roughly:

• 直到 emphasizes the endpoint: up until that time
• 等到 emphasizes when the time comes that...

In this sentence, 直到 gives a slightly stronger not until feeling, which matches 才 very well.

All of them relate to repairing, but the tone is different:

• 修 = everyday, simple, very common
• 修理 = repair; fairly common and neutral
• 维修 = more formal, often used for equipment, systems, facilities, or technical maintenance

Because 水管 and 供水 sound a bit more formal or public-service related, 维修 fits the sentence well.

For example:

• 修水管 = everyday speech
• 维修水管 = a bit more formal/technical

Both are understandable, but 维修 suits this sentence’s style.