CA Civ Proc Code Section 2031.290

(a)

The demand for inspection, copying, testing, or sampling, and the response to it, shall not be filed with the court.

(b)

The party demanding an inspection, copying, testing, or sampling shall retain both the original of the demand, with the original proof of service affixed to it, and the original of the sworn response until six months after final disposition of the action. At that time, both originals may be destroyed, unless the court, on motion of any party and for good cause shown, orders that the originals be preserved for a longer period.