Determining the precise watering requirements for a bonsai tree can be challenging, as factors such as weather conditions, humidity levels, pot size, and soil composition all play a role. 

Nonetheless, it is crucial to understand that proper watering is the cornerstone of bonsai care and significantly impacts tree health. Improper watering is the leading cause of bonsai tree fatalities. 

A key guideline is to monitor your tree daily to ensure the soil remains moist, watering only in the evening to avoid sudden temperature changes that could shock the tree. It is essential to prevent the soil from completely drying out and to avoid watering multiple trees on a set schedule, as each tree's watering needs must be assessed individually to prevent overwatering. 

With experience, you will develop the ability to determine when your tree requires watering simply by observing the soil. Typically, bonsai trees need to be watered every one to two days, though in warm weather conditions or outdoor settings, watering may be necessary multiple times per day. 

When watering your bonsai, it is advisable to use a hose with a fine rose attachment or a watering can with a similar feature to avoid soil erosion and potential tree damage. Submersion, where the tree is placed in a container of water for a few minutes, can also be an effective watering method, particularly for trees with compacted soil. 

For larger collections or convenience, a drip system may be installed to automate watering. 

However, it is essential to monitor individual tree requirements and adjust watering accordingly based on seasonal changes. 

When selecting water for your bonsai, rainwater is preferred for its purity and ability to flush out mineral deposits. If rainwater is unavailable, tap water can be used after allowing it to sit overnight to allow chlorine to dissipate. Distilled or purified water may also be used, but supplemental nutrients may be required. 

Watering practices should be adjusted during different seasons, with trees typically requiring less water during dormancy in winter. Tropical and indoor bonsai trees should remain indoors during winter, with watering routines unchanged. In conclusion, proper watering techniques are vital for maintaining the health and vitality of bonsai trees. 

By following these guidelines and adapting to seasonal changes, you can ensure the longevity and well-being of your bonsai collection. Avoid using high-pressure water streams, as they can cause damage to branches and soil.