Introduction
In an irregularly grown town, the suitable layout for a water supply distribution system is a dead-end system. This system is designed to efficiently deliver water to consumers while minimizing the possibility of contamination and ensuring adequate pressure throughout the network.

Advantages of a Dead-End System
1. Simple and Cost-Effective: The dead-end system is relatively simple to design and construct, making it a cost-effective option for an irregularly grown town.
2. Easy Maintenance: The dead-end system allows for easier maintenance and repair of pipelines as the network is less complex compared to other layouts.
3. Reduced Contamination Risk: The dead-end system reduces the risk of water contamination as it minimizes the chances of water stagnation and the formation of biofilms in the pipelines.
4. Efficient Pressure Management: A dead-end system ensures that adequate pressure is maintained throughout the network, allowing for efficient delivery of water to consumers.

Disadvantages of Other Systems
1. Grid Iron System: This system involves a complex network of pipelines intersecting at regular intervals, which can be difficult to implement in an irregularly grown town. It may also lead to water stagnation in certain areas.
2. Ring System: In a ring system, pipelines form a closed loop, which may result in water stagnation and reduced pressure in certain areas. It can also be challenging to implement in an irregularly grown town.
3. Radial System: A radial system consists of pipelines radiating from a central point. While it can be effective for water supply in a regular layout, it may not be suitable for an irregularly grown town as it may require significant modifications and may result in uneven pressure distribution.

Conclusion
The dead-end system is the most suitable layout for a water supply distribution system in an irregularly grown town. It provides simplicity, cost-effectiveness, easy maintenance, reduced contamination risk, and efficient pressure management. Other systems like the grid iron, ring, and radial systems may not be as effective or feasible in such a scenario.