San Marcos runs a permanent Household Hazardous Waste Drop-Off and Reuse Center at 634 E Hopkins, in the city traffic yard across from the big HEB. The city holds a permit from the Texas Commission on Environmental Quality to operate it, and the permit is why the residency rule is strict: only waste from residential households in San Marcos and Hays County is accepted, and staff cannot take anything generated by a business. Proof of Hays County residency is required. The facility works to a 300lb limit.

Per-visit caps apply to the commonest materials. Oil, fuel and antifreeze are limited to twelve quarts per visit; car batteries to three; and paint to a maximum of six five-gallon buckets. Medical sharps are accepted but must arrive in a proper sharps container. Ammunition is not taken here at all — it goes to the San Marcos Police Department, and anyone with more than a case should call ahead on (512) 754-2203.

The reuse side is the reason to visit even if you have nothing to drop off. Anything arriving in good condition — paint, cleaning supplies, fertilisers, pesticides, automotive chemicals — is put out in the Reuse Center, and Hays County residents may take up to five items each, free. A separate Reuse Warehouse at the same address takes and gives away household goods in good condition to San Marcos garbage customers, limited to ten items, on Saturdays 8am to noon.

The city does not publish a charge for the drop-off on its own page. The City of Buda describes the facility as providing free disposal to all Hays County residents, but since that is another city's page rather than San Marcos's own, we record the fee as unpublished rather than state it as free.

Check the hours before travelling, because the city publishes two versions. Its Household Hazardous Waste Facility page gives Fridays noon to 3:30pm and Saturdays 8am to noon. A second city page gives Tuesdays and Fridays, noon to 3:30pm. Neither carries an effective date, so call Resource Recovery on (512) 393-8412 first.