Even if a piped water supply is safe at its source, it is not always safe by the time it reaches the tap.

即使管道供水系统在水源处安全的，等水到达龙头时就不一定总是安全的了。

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Even if a piped water supply is safe at its source.

即使管道供水系统在水源处是安全的。

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Even if a piped water supply is safe at its source.

即使管道供水系统在水源处是安全的。

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