South Convent Avenue, Barrio Viejo.

Site & client

The lot is on South Convent Avenue between West Cushing and West Simpson, two blocks west of the El Charro Café on West Cushing and a fifteen-minute walk from Tucson Convention Center. The 1908 adobe is part of a row of seven contiguous structures, all on the National Register and contributing structures to the Barrio Histórico Historic District. The owner is a Tucson-born high-school history teacher who inherited the property from his grandmother in 2021 and spent two years restoring the lime-plaster facade and the floors before contacting us.

The lot is 40 × 110 feet, with the adobe occupying the front 60 feet and a small patio of 0.05 acres at the rear. There is no front yard. The roof is a parapet flat-roof construction typical of Sonoran-style adobes from the period, with rain water exiting via four canales (decorative drain spouts at the parapet edge) onto the courtyard or the street.

The site walk

October 11, 2024. Two hours, the owner on hand, with a representative from the Tucson Historic Preservation Office joining for the second hour at our request. We mapped the four canale outlets, the existing decorative cobblestone surface in the patio, the small AC condenser unit at the rear corner, and the only space large enough to accept a cistern: an 8 × 8 foot pocket between the rear bedroom wall and the alley fence. The HPO representative was mostly concerned with visibility from the public ROW (none, in our proposed location) and reversibility (we agreed to install on a removable concrete pad rather than disturbing the adobe footing).

What we built

The build ran four crew-days. The build had to be slow on the adobe side: any percussion against an unreinforced 1908 adobe wall risks cracking the lime plaster, so we hand-drilled the canale-to-cistern transitions with a low-RPM rotary tool over an afternoon rather than the usual hammer drill. The major elements:

• CIS-1 · 1,500-gal Bushman SLI1500 mocha tucked behind a 6-foot coyote-fence panel made from local ocotillo (we sourced the panel from El Río Ocotillo, a small fence-panel maker in Marana). Tank fed by two of the four canales via 2″ aluminum extensions painted to match the parapet. Pump is a small Grundfos SCALA1; controller a Hunter X-Core 2-zone.
• EARTH-1 · two small basins. A 25-ft³ basin under the existing pomegranate at the rear of the patio (overflow path from the cistern), and an 8-ft³ basin at the foot of the courtyard wall under a young Texas mountain laurel.
• COND-1 · AC condensate to existing pomegranate. A short 1/2″ PEX run from the rear-corner condenser unit to the same basin as the cistern overflow.

By the numbers · 2025-03 to 2026-04

The 1,580 sf roof catchment is small for a Tucson cistern install — most of our work is on lots with at least 2,000 sf. Capture is correspondingly modest, but the system carries the existing pomegranate and Texas mountain laurel through the entire summer without supplemental municipal water.

Historic-district lessons

This was our first formal historic-district install and we've done two more since (one in Armory Park, one in West University). Three things we learned:

Bring HPO to the site walk. The Tucson Historic Preservation Office staff is helpful, technical, and not adversarial; the more they understand the proposed work up front, the less likely the review process is to slow the build. We schedule them whenever possible.

The screen is the difference. A cistern itself is rarely the issue; visibility of a tank, especially from the public ROW, is the issue. We've had cisterns approved at every review when they are screened with a coyote fence, ocotillo wall, or matched-stucco-and-stone enclosure. We've never had an unscreened tank approved.

Reversibility matters. The single concession that has gotten every historic-district build approved is "every fastener can be removed and the original structure restored without specialized labor." This is also good practice for an adobe whose plaster you don't want to disturb.