Data shows BP PLC has failed to collect the maximum amount of oil it is capable of using its two current containment devices on any single day since both were in place.

Since June 16, the oil giant has been using a cap over the gusher to contain some of the oil and a vessel on the surface that is bringing up oil through undersea lines.

Together, the two devices can recover 20,000 barrels to 28,000 barrels, or up to nearly 1.2 million gallons, of oil per day.

An Associated Press review of data obtained from the company shows the closest BP has gotten was 27,090 barrels on June 22, the day before an undersea camera bumped the cap and forced BP to remove it for more than 10 hours.

Since the cap was put back on, the highest amount of oil collected on any single day was 25,220 barrels on Tuesday.

BP insists there is nothing wrong with the two devices. Spokesman Toby Odone said Friday the volumes vary from day to day depending on various factors, including the proportion of gas and oil in the hydrocarbons coming out of the well, the sea state and the stability of the processing plant aboard the vessels.

A third system BP has been looking to bring online to raise capacity to between 40,000 barrels and 53,000 barrels per day was supposed to be in place by the end of June. However, bad weather put it behind schedule, and it is now due on line around the middle of next week, according to the company.