Why are the toilets on the train connected directly to the tracks?

As uncomfortable as that sounds today, when these systems were introduced, they made a lot of sense.

A Look Back: Early Train Travel
When passenger trains first became widespread in the 19th century, comfort was a secondary concern.Travel & Transportation

Early trains:

Were slow

Had short routes

Made frequent stops

Didn’t prioritize onboard sanitation

Eventually, as journeys became longer, toilets became a necessity.Waste Management

But engineers faced a challenge:
How do you add toilets to a moving vehicle with no plumbing connections?

The simplest solution won.

Why Gravity Was the Easiest Answer
Early railway designers worked with limited technology.

There were:

No compact waste tanks

No odor-control systems

No vacuum toilets