Final answer:
You should drain the oil and water from the bottom of an air storage tank without automatic drains daily if the compressor is used daily, and possibly more frequently depending on environmental factors and usage.
Step-by-step explanation:
If you do not have automatic tank drains for your air storage tank, it is important to drain the oil and water regularly to prevent air system contamination. The frequency of drainage can vary, but a general rule of thumb is to do so every day if the compressor is in daily use. This regular maintenance prevents the accumulation of moisture which can cause rust and the potential failure of the air system. In some environments or under heavier use, more frequent drainage may be necessary.