**Explanation:**

The organic content of water used for making concrete is specified in IS : 456-2000, which is the Indian Standard code of practice for plain and reinforced concrete. According to this standard, the organic content of water should not exceed 200 mg/L.

**Reasoning:**

The presence of organic matter in water used for making concrete can have a detrimental effect on the properties of the concrete. Organic matter can interfere with the hydration process and inhibit the development of strength in the concrete. It can also cause discoloration, reduce durability, and affect the bond between the concrete and reinforcement.

**Importance of Organic Content Limit:**

Limiting the organic content of water used for making concrete to 200 mg/L ensures that the water is relatively free from organic impurities. This helps in producing concrete with desired properties and performance characteristics.

**Impact of Excessive Organic Content:**

If the organic content of water exceeds the specified limit of 200 mg/L, it can lead to the following issues:

1. Delayed Setting: Organic matter can act as a retarder and delay the setting time of concrete.

2. Reduced Strength: Organic matter can interfere with the hydration process and inhibit the development of strength in the concrete.

3. Discoloration: Organic matter can cause discoloration in the concrete, resulting in an undesirable appearance.

4. Reduced Durability: Organic matter can reduce the durability of concrete by promoting the growth of microorganisms and causing biological deterioration.

5. Poor Bonding: Organic matter can affect the bond between the concrete and reinforcement, leading to reduced structural integrity.

**Conclusion:**

To ensure the quality and performance of concrete, it is important to adhere to the specified limit of 200 mg/L for the organic content of water used in its preparation. This helps in achieving the desired properties, strength, and durability of the concrete structure.