Stone ware pipes are

The correct answer is Option A: Highly resistant to sulphide corrosion.

In Wastewater Engineering, pipes carry sewage, which can be quite harsh. One of the biggest problems is sulphide corrosion. Here's how it happens:

1. Wastewater contains materials that can be broken down by tiny bacteria.

2. These bacteria produce a gas called hydrogen sulphide (H₂S).

3. When this gas mixes with moisture inside the pipe, especially near the top, it can form sulphuric acid.

4. Sulphuric acid is highly corrosive and can damage materials such as concrete over time.

Stoneware pipes are made from a special type of clay that is baked at very high temperatures. This process makes them dense, hard, and chemically inert. Chemically inert means they do not react easily with chemicals, including strong acids such as sulphuric acid.

Therefore, stoneware pipes are highly resistant to sulphide corrosion. This is a major advantage because they can provide long service life in the corrosive environment of sewerage systems.

Option B: Highly impervious
This statement is also a good property of stoneware pipes. Stoneware is dense and has low permeability, which helps prevent water from passing through the pipe walls. However, resistance to sulphide corrosion is the more relevant distinguishing property in this question.

Option C: Hydraulically efficient because of their smooth interior surface
Stoneware pipes generally have a smooth interior surface, which helps wastewater flow with relatively low friction. However, hydraulic efficiency is not their most distinctive advantage, as several other pipe materials also provide smooth internal surfaces.

Option D: Especially suited to pressure pipes
This statement is incorrect. Stoneware pipes are relatively brittle and can crack or break when subjected to high internal pressure or impact. They are mainly used in gravity-flow sewerage systems rather than pressure pipelines.

Hence, the correct answer is Option A: Highly resistant to sulphide corrosion.