A patient excretes a large volume of very dilute urine on a continuing basis. This is may be due to

arterial hypertension

Explanation:

When increasing the arterial pressure, in the renal glomerulus the filtration of liquids increases since the liquids diffuse from zones of greater pressure to less pressure.

In this way, the liquid content of the urine increases and it is more diuluid because this does not apply to proteins or solutes, since these are affected by discrepancies in concentrations and not in pressures.