Which of the following materials can be used for blockouts?

The use of rubber as a material for blockouts is favored in many applications related to septic tank systems because it is flexible, durable, and resistant to various environmental factors, including chemicals and temperature changes. Rubber can provide a good seal, which is essential to prevent leaks and maintain the integrity of the septic system. Its cushioning properties also allow it to absorb vibrations and settle without cracking, making it suitable for maintaining the physical integrity of the septic system over time.

In contrast, glass, while a strong material, does not provide the necessary flexibility and sealing capabilities required for effective blockouts in septic systems. Concrete, although robust, can be prone to cracking under shifting soil conditions and is not ideal for creating seals. Brick, while it has some durability, lacks the sealing properties of rubber and may not accommodate the necessary flexibility required for blockouts in various environmental conditions. Therefore, rubber is the preferred choice for such applications due to its unique attributes.