Maximum quantity of water needed per 50kg of cement for m25, M20 and M15 concrete will depend on concrete mix design, water-cement ratio, the workability, strength, and durability of the concrete. However, as per general guidelines, the typical maximum amount of water per 50 kg bag of cement for M25 is about 27 liters, for M20 about 30 liters, for M15 about 32 liters and for M10 about 34 liters.

The water-cement ratio (W/C ratio) is a critical factor in concrete mix design, determining the workability, strength, and durability of the concrete.

**Here are the typical maximum water quantities per 50 kg bag of cement for M25, M20, and M15 grades of concrete:**

- M25 Grade Concrete: The typical mix ratio for M25 grade concrete is 1:1:2, which means 1 part cement is mixed with 1 part sand and 2 parts aggregate. The maximum water-cement ratio for M25 grade concrete is usually around 0.54. So, for a 50 kg bag of cement, the maximum water required would be approximately 27 liters.
- M20 Grade Concrete: The typical mix ratio for M20 grade concrete is 1:1.5:3, which means 1 part cement is mixed with 1.5 parts sand and 3 parts aggregate. The maximum water-cement ratio for M20 grade concrete is typically around 0.60. For a 50 kg bag of cement, the maximum water required would be approximately 30 liters.
- M15 Grade Concrete: The typical mix ratio for M15 grade concrete is 1:2:4, which means 1 part cement is mixed with 2 parts sand and 4 parts aggregate. The maximum water-cement ratio for M15 grade concrete is usually around 0.64. Therefore, for a 50 kg bag of cement, the maximum water required would be approximately 32 liters.
- M10 Grade Concrete: The typical mix ratio for M15 grade concrete is 1:3:6, which means 1 part cement is mixed with 3 parts sand and 6 parts aggregate. The maximum water-cement ratio for M10 grade concrete is usually around 0.68. Therefore, for a 50 kg bag of cement, the maximum water required would be approximately 34 liters.
- M7.5 Grade Concrete: The typical mix ratio for M15 grade concrete is 1:4:8, which means 1 part cement is mixed with 4 parts sand and 8 parts aggregate. The maximum water-cement ratio for M7.5 grade concrete is usually around 0.90. Therefore, for a 50 kg bag of cement, the maximum water required would be approximately 45 liters.
- M5 Grade Concrete: The typical mix ratio for M5 grade concrete is 1:5:10, which means 1 part cement is mixed with 5 parts sand and 10 parts aggregate. The maximum water-cement ratio for M5 grade concrete is usually around 1.2. Therefore, for a 50 kg bag of cement, the maximum water required would be approximately 60 liters.

**Conclusions:-**

In general, the typical maximum amount of water per 50 kg bag of cement for M25 is about 27 liters, for M20 about 30 liters, for M15 about 32 liters and for M10 about 34 liters.