A water filtration system working properly becomes part of the background. The kitchen tap produces clean-tasting water without the chloramine character that SAWS-treated tap water carries. Maintenance happens on a schedule. Performance stays consistent. When something changes — the taste returns, the flow from the filtered faucet drops, the system behaves differently than it did — most San Antonio homeowners don't immediately know whether they're dealing with a routine maintenance event, a repair, or a sign that a system has reached the end of its useful life. This post covers the most common water filtration problems in San Antonio homes, what causes them in the context of Edwards Aquifer water, how to diagnose what you're dealing with, and when a service call is the right next step.

What makes San Antonio water a specific challenge for filtration systems

Understanding why San Antonio filtration systems fail the way they do starts with understanding the Edwards Aquifer. Unlike Houston or Dallas, which draw from surface water reservoirs that vary with season and rainfall, San Antonio draws primarily from a limestone-filtered artesian aquifer that delivers essentially the same water month after month. Edwards Aquifer water at the tap typically measures between 15 and 20 GPG of hardness, year-round, without the seasonal variation that surface water cities experience.

That consistency is a maintenance advantage in some ways — there are no seasonal spikes that catch a change schedule by surprise, no post-storm turbidity events that load a pre-filter ahead of schedule. But it also means the filtration system is working against 15 to 20 GPG hardness continuously, without the softer periods that surface water systems occasionally deliver. Media exhaustion in San Antonio happens at a steady, predictable rate rather than an uneven one. A filter that's two months past its change date in San Antonio has been working against full Edwards Aquifer hardness for every one of those two months.

SAWS treats with chloramines — a chlorine-ammonia compound more stable than free chlorine and considerably harder to remove. A drinking water filtration system configured with standard activated carbon rather than catalytic carbon is the single most common underlying specification problem in San Antonio homes with persistent taste issues that service can't resolve. Standard carbon handles free chlorine. Catalytic carbon handles chloramines. In San Antonio, only catalytic carbon does the job.

The taste came back — media exhaustion on Edwards Aquifer water

The most common water filtration problem in San Antonio homes is filter media exhaustion — the carbon media has reached the end of its service life and is no longer removing chloramines effectively. The tap water tastes like SAWS water again.

Carbon media removes contaminants through adsorption — contaminants bind to available surface area on the carbon — and once that surface area is saturated, the media passes contaminants through rather than capturing them. In San Antonio, at 15 to 20 GPG hardness year-round, media loads at a steady rate that's higher than in lower-hardness markets. The rate is predictable, which is an advantage: a change schedule calibrated to your actual household usage and your tap's hardness should keep the system performing consistently without the seasonal surprises that DFW or Houston surface water can produce.

The fix is a filter cartridge replacement. If the taste comes back noticeably earlier than expected — before the scheduled change interval — there are two likely explanations: household water usage has increased since the interval was set, or the incoming hardness at your specific address is toward the higher end of the 15 to 20 GPG range and loading the media faster than the schedule assumes. A water test at your tap gives you the actual hardness number needed to calibrate the interval correctly.

If a fresh cartridge replacement doesn't improve the taste to the expected degree, the media type is worth investigating. A system specified with standard carbon rather than catalytic carbon will never fully address San Antonio's chloramine treatment — new cartridges of the wrong media type won't fix a problem that's a specification issue rather than an exhaustion issue.

Reduced flow from the filtered faucet

A filtered faucet producing noticeably less water than it used to points to one of three things: a loaded sediment pre-filter, a carbon cartridge loaded to the point of flow restriction, or — for reverse osmosis systems — a fouled or aging membrane.

Sediment pre-filters capture particulate matter before it reaches the primary filtration media. In San Antonio, Edwards Aquifer water is lower in sediment than Houston or DFW surface water — the aquifer's limestone filtration removes most particulate load before the water reaches the surface. Pre-filters in San Antonio homes load more slowly than in surface water markets, which means a pre-filter that's been in service for its full nominal interval and is just now causing flow restriction is behaving as expected. Replacement should restore flow.

If flow is still reduced after a fresh pre-filter, the carbon cartridge is the next variable. A carbon cartridge loaded to the point of flow restriction has usually been in service well past its effective service life — the taste problem likely returned before the flow problem did, and may have been overlooked. Replacing the carbon stage should restore full flow.

For reverse osmosis systems, reduced production rate — the tank refilling more slowly than it used to, or faucet flow that feels weaker — indicates a membrane that's approaching the end of its service life. In San Antonio, where Edwards Aquifer water is relatively free of the organic matter and turbidity variation that can foul RO membranes faster in surface water markets, membrane service life is more predictable. A two-to-five-year membrane service life, properly maintained, is a reasonable expectation for most San Antonio RO installations.

The Edwards Aquifer consistency advantage — and what it means for maintenance

San Antonio filtration maintenance is more predictable than in surface water markets, and that predictability is worth understanding as a diagnostic tool.

In Dallas-Fort Worth, filtration systems can exhibit seasonal performance patterns — declining in summer when reservoir levels drop and hardness increases, recovering somewhat in fall. In Houston, storm events can spike pre-filter loading. Neither of these patterns applies to San Antonio. Edwards Aquifer water is 15 to 20 GPG year-round. There are no seasonal turbidity events, no post-rainfall dilution, no summer hardness spikes that catch a maintenance schedule by surprise.

This means if a San Antonio filtration system is declining in performance, the explanation is almost never "the water changed." It's almost always one of three things: the media has exhausted on schedule (expected, remedied by replacement), the media was exhausted early because usage or actual hardness is higher than the schedule assumed (remedied by shortening the interval), or the system was never correctly specified for chloramine treatment in the first place (remedied by replacement with catalytic carbon media).

The absence of seasonal variation also means that if a San Antonio homeowner has established a change schedule that works — clean taste maintained consistently between changes — it will continue to work the same way in July as in January. That stability makes it easier to build a reliable maintenance routine than in markets where seasonal variation requires schedule adjustments throughout the year.

RO system running continuously or producing slowly

An under-sink reverse osmosis system that runs continuously — audible for extended periods after water has been drawn — or that fills its storage tank noticeably more slowly than it used to typically indicates a shutoff valve problem, a tank air pressure issue, or a membrane nearing the end of its service life.

RO systems fill a storage tank and stop producing when the tank is full, controlled by a shutoff valve that responds to tank pressure. A shutoff valve that has failed — a predictable wear item — allows the system to run past the point of full tank capacity, sending water to drain continuously. This is a repair: the shutoff valve needs replacement. Left unaddressed, a continuously running RO system wastes water and can stress other components.

A storage tank with depleted air pressure causes a related problem. The pressurized air bladder in an RO tank helps push stored water out when the faucet is opened. If the air charge has dropped below specification — typically 6 to 8 PSI for an empty tank — the system produces water more slowly and runs longer trying to keep up, and faucet flow may feel slow or weak even when the tank should be full. Checking tank air pressure with a standard tire gauge and correcting it is a maintenance step that often resolves "slow faucet" complaints without any component replacement.

For San Antonio RO systems, membrane service life is relatively consistent — Edwards Aquifer water's low turbidity and organic matter content means membranes aren't subject to the organic fouling that can shorten service life in surface water markets. A membrane that has been in service for three or more years and is showing reduced production is likely due for replacement on schedule rather than failing prematurely.

Softener problems that affect filtration downstream

For San Antonio households running both a whole home water softener and an under-sink drinking water filtration system, a softener underperforming on Edwards Aquifer water can increase the mineral load delivered to the downstream filtration system — causing faster media exhaustion and potentially hard water signs in the house even when the softener appears to be operating.

Edwards Aquifer water at 15 to 20 GPG is consistent, which makes softener sizing and regeneration scheduling more straightforward than in variable-hardness surface water markets. A softener properly sized for San Antonio water and configured with demand regeneration should handle Edwards Aquifer hardness reliably. A softener on a fixed timer schedule that was set for a lower hardness estimate may be regenerating less frequently than the actual 15 to 20 GPG incoming water requires — particularly if the household's water usage has grown since the schedule was last configured.

Bridging — salt clumping in the brine tank that creates a hollow dome above the water level, preventing brine from forming correctly for regeneration — is a maintenance issue specific to salt-based softeners. A softener that appears to have salt in the tank but is regenerating with inadequate brine will not soften effectively. Checking for salt bridges by gently probing the salt level in the brine tank is a useful diagnostic step when a softener seems to be underperforming despite apparent salt availability.

For San Antonio softeners, the consistency of Edwards Aquifer water makes long-term resin performance more predictable than in surface water markets where iron content or turbidity can accelerate resin fouling. Resin beds in properly maintained San Antonio softeners typically approach the fifteen-to-twenty-year service life under normal conditions.

Repair vs. replacement for San Antonio filtration systems

Most San Antonio filtration problems are maintenance events — cartridge replacement resolves the majority of performance issues, and the predictability of Edwards Aquifer water makes it easier to stay ahead of them than in variable-hardness markets. The repair vs. replacement question arises when a system is old enough or was specified incorrectly enough that continued service doesn't produce the results a new system would.

For carbon filtration systems: a system older than eight to ten years, or one that was installed with standard carbon rather than catalytic carbon for SAWS's chloramine treatment, is a candidate for replacement rather than continued service. New cartridges of the wrong media type won't resolve a chloramine taste issue. A new system correctly specified with catalytic carbon will outperform an older standard-carbon system regardless of how recently the cartridges were changed.

For reverse osmosis systems: membranes, shutoff valves, and pressure components all have service lives that are reasonably predictable in San Antonio's consistent water. An RO system older than ten to twelve years requiring repeated component replacements is worth evaluating for full replacement against the expected cost of continued repair. New RO systems configured with catalytic carbon pre-filtration for SAWS water will perform reliably and predictably on Edwards Aquifer supply.

For water softeners: resin beds in San Antonio typically approach fifteen to twenty years under normal conditions, given the relatively clean Edwards Aquifer source. A softener failing to soften adequately despite correct settings and salt availability — and that hasn't responded to regeneration schedule adjustment — warrants a resin assessment before assuming full replacement is needed.

When to call for service in San Antonio

Many filtration issues are homeowner-managed maintenance: a filter cartridge change, a salt refill, checking and correcting tank air pressure. Others need a service call.

Call for service when: flow reduction persists after pre-filter replacement. Taste issues return well before the scheduled change interval and a fresh catalytic carbon cartridge doesn't resolve them. An RO system runs continuously, refills noticeably more slowly than it used to, or produces weaker flow than expected. A water softener produces hard water before the end of its expected regeneration cycle despite correct salt and settings. There's unexplained moisture around system components. The system makes sounds it didn't make before.

For San Antonio households where the filtration system was installed by a company no longer operating in the area, an independent evaluation — checking media type, whether catalytic carbon is specified for SAWS chloramine treatment, whether the softener is sized for Edwards Aquifer hardness, and whether regeneration settings reflect actual household usage — is often more useful than reactive repair of components that may be fundamentally mismatched to the water.

Dupure serves the San Antonio area and provides water filtration system service, evaluation, and maintenance for both Dupure-installed systems and third-party equipment. If your filtration system isn't performing the way it should, or if you're not sure whether what you're experiencing is a maintenance issue, a specification problem, or a repair — the starting point is the same as for a new installation: a clear look at your actual water and an honest assessment of what the system is and isn't doing.