The large amount of fish waste in the form of fish washing water used by the community has resulted in the disposal of fish waste increasing day by day. Disposing of fish waste directly into the environment without processing will not only cause a very strong stench but can also disturb the environment. With KKN, students are expected to be able to become an active, creative and innovative part of society, involved in the dynamics that occur in society. This activity aims to provide a solution to reduce household waste by making effective liquid organic fertilizer using rice washing water and fish washing water as basic ingredients. Rice washing water is rich in carbohydrates and B vitamins, while fish washing water is high in protein and minerals, both of which have the potential to be a source of plant nutrition. The process for making liquid organic fertilizer requires MOL of rice water and fish washing water and involves fermentation for 20 days. The fermentation results showed a significant increase in the content of nitrogen, phosphorus and potassium, which are essential nutrients for plant growth. This fertilizer is environmentally friendly and makes use of household waste which is often wasted. Thus, liquid organic fertilizer from rice washing water and fish washing water can be an effective and sustainable alternative for organic farming.